1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158
//! This crate provides heap profiling and ad hoc profiling capabilities to //! Rust programs, similar to those provided by [DHAT]. //! //! [DHAT]: https://www.valgrind.org/docs/manual/dh-manual.html //! //! The heap profiling works by using a global allocator that wraps the system //! allocator, tracks all heap allocations, and on program exit writes data to //! file so it can be viewed with DHAT's viewer. This corresponds to DHAT's //! `--mode=heap` mode. //! //! The ad hoc profiling is via a second mode of operation, where ad hoc events //! can be manually inserted into a Rust program for aggregation and viewing. //! This corresponds to DHAT's `--mode=ad-hoc` mode. //! //! # Motivation //! //! DHAT is a powerful heap profiler that comes with Valgrind. This crate is a //! related but alternative choice for heap profiling Rust programs. DHAT and //! this crate have the following differences. //! - This crate works on any platform, while DHAT only works on some platforms //! (Linux, mostly). (Note that DHAT's viewer is just HTML+JS+CSS and should //! work in any modern web browser on any platform.) //! - This crate causes a much smaller slowdown than DHAT. //! - This crate requires some modifications to a program's source code and //! recompilation, while DHAT does not. //! - This crate cannot track memory accesses the way DHAT does, because it does //! not instrument all memory loads and stores. //! - This crate does not provide profiling of copy functions such as `memcpy` //! and `strcpy`, unlike DHAT. //! - The backtraces produced by this crate may be better than those produced //! by DHAT. //! - DHAT measures a program's entire execution, but this crate only measures //! what happens within the scope of `main`. It will miss the small number of //! allocations that occur before or after `main`, within the Rust runtime. //! //! # Configuration //! //! In your `Cargo.toml` file, as well as specifying `dhat` as a dependency, //! you should enable source line debug info: //! ```toml //! [profile.release] //! debug = 1 //! ``` //! //! # Usage (heap profiling) //! //! For heap profiling, enable the global allocator by adding this code to your //! program: //! ``` //! use dhat::{Dhat, DhatAlloc}; //! //! #[global_allocator] //! static ALLOCATOR: DhatAlloc = DhatAlloc; //! ``` //! Then add the following code to the very start of your `main` function: //! ``` //! # use dhat::Dhat; //! let _dhat = Dhat::start_heap_profiling(); //! ``` //! `DhatAlloc` is slower than the system allocator, so it should only be //! enabled while profiling. //! //! # Usage (ad hoc profiling) //! //! [Ad hoc profiling] involves manually annotating hot code points and then //! aggregating the executed annotations in some fashion. //! //! [Ad hoc profiling]: https://github.com/nnethercote/counts/#ad-hoc-profiling //! //! To do this, add the following code to the very start of your `main` //! function: //!``` //! # use dhat::Dhat; //! let _dhat = Dhat::start_ad_hoc_profiling(); //! ``` //! Then insert calls like this at points of interest: //! ``` //! dhat::ad_hoc_event(100); //! ``` //! For example, imagine you have a hot function that is called from many call //! sites. You might want to know how often it is called and which other //! functions called it the most. In that case, you would add a `ad_hoc_event` //! call to that function, and the data collected by this crate and viewed with //! DHAT's viewer would show you exactly what you want to know. //! //! The meaning of the integer argument to `ad_hoc_event` will depend on //! exactly what you are measuring. If there is no meaningful weight to give to //! an event, you can just use `1`. //! //! # Running //! //! For both heap profiling and ad hoc profiling, the program will run //! normally. When the `Dhat` value is dropped at the end of `main`, some basic //! information will be printed to `stderr`, like so: //! ```text //! dhat: Total: 1,256 bytes in 6 blocks //! dhat: At t-gmax: 1,256 bytes in 6 blocks //! dhat: At t-end: 1,256 bytes in 6 blocks //! dhat: The data in dhat-heap.json is viewable with dhat/dh_view.html //! ``` //! A file called `dhat-heap.json` (for heap profiling) or `dhat-ad-hoc.json` //! (for ad hoc profiling) will be written. It can be viewed in DHAT's viewer. //! //! If you don't see this output, it may be because your program called //! `std::process::exit`, which terminates a program without running any //! destructors. To work around this, explicitly call `drop` on the `Dhat` //! value just before the call to `std::process:exit`. //! //! # Viewing //! //! Open a copy of DHAT's viewer, version 3.17 or later. There are two ways to //! do this. //! - Easier: Use the [online version]. //! - Harder: Clone the [Valgrind repository] with `git clone //! git://sourceware.org/git/valgrind.git` and open `dhat/dh_view.html`. //! (There is no need to build any code in this repository.) //! //! [online version]: https://nnethercote.github.io/dh_view/dh_view.html //! [Valgrind repository]: https://www.valgrind.org/downloads/repository.html //! //! Then click on the "Load…" button to load `dhat-heap.json` or //! `dhat-ad-hoc.json`. //! //! DHAT's viewer shows a tree with nodes that look like this. //! ```text //! PP 1.1/6 { //! Total: 1,024 bytes (81.53%, 3,335,504.89/s) in 1 blocks (16.67%, 3,257.33/s), avg size 1,024 bytes, avg lifetime 61 µs (19.87% of program duration) //! Max: 1,024 bytes in 1 blocks, avg size 1,024 bytes //! At t-gmax: 1,024 bytes (81.53%) in 1 blocks (16.67%), avg size 1,024 bytes //! At t-end: 1,024 bytes (81.53%) in 1 blocks (16.67%), avg size 1,024 bytes //! Allocated at { //! #1: 0x10c1e4108: <alloc::alloc::Global as core::alloc::AllocRef>::alloc (alloc.rs:203:9) //! #2: 0x10c1e4108: alloc::raw_vec::RawVec<T,A>::allocate_in (raw_vec.rs:186:45) //! #3: 0x10c1e4108: alloc::raw_vec::RawVec<T,A>::with_capacity_in (raw_vec.rs:161:9) //! #4: 0x10c1e4108: alloc::raw_vec::RawVec<T>::with_capacity (raw_vec.rs:92:9) //! #5: 0x10c1e4108: alloc::vec::Vec<T>::with_capacity (vec.rs:355:20) //! #6: 0x10c1e4108: std::io::buffered::BufWriter<W>::with_capacity (buffered.rs:517:46) //! #7: 0x10c1e4108: std::io::buffered::LineWriter<W>::with_capacity (buffered.rs:925:29) //! #8: 0x10c1e4108: std::io::buffered::LineWriter<W>::new (buffered.rs:905:9) //! #9: 0x10c1e4108: std::io::stdio::stdout::stdout_init (stdio.rs:543:65) //! #10: 0x10c1e4108: std::io::lazy::Lazy<T>::init (lazy.rs:57:19) //! #11: 0x10c1e4108: std::io::lazy::Lazy<T>::get (lazy.rs:33:18) //! #12: 0x10c1e4108: std::io::stdio::stdout (stdio.rs:536:25) //! #13: 0x10c1e4ccb: std::io::stdio::print_to::{{closure}} (stdio.rs:890:13) //! #14: 0x10c1e4ccb: std::thread::local::LocalKey<T>::try_with (local.rs:265:16) //! #15: 0x10c1e4ccb: std::io::stdio::print_to (stdio.rs:879:18) //! #16: 0x10c1e4ccb: std::io::stdio::_print (stdio.rs:907:5) //! #17: 0x10c0d6826: heap::main (heap.rs:9:5) //! } //! } //! ``` //! Full details about the output are in the [DHAT documentation]. //! //! [DHAT documentation]: https://valgrind.org/docs/manual/dh-manual.html //! //! Note that DHAT uses the word "block" rather than "allocation" to refer to //! the memory allocated by a single heap allocation operation. //! //! When heap profiling, this crate doesn't track memory accesses (unlike DHAT) //! and so the "reads" and "writes" measurements are not shown within DHAT's //! viewer, and "sort metric" views involving reads, writes, or accesses are //! not available. //! //! The backtraces produced by this crate are trimmed to reduce output file //! sizes and improve readability in DHAT's viewer. //! - Only one allocation-related frame will be shown at the top of the //! backtrace. That frame may be a function within `alloc::alloc`, a function //! within this crate, or a global allocation function like `__rg_alloc`. //! - Common frames at the bottom of backtraces, below `main`, are omitted. use backtrace::SymbolName; use lazy_static::lazy_static; use rustc_hash::FxHashMap; use serde::Serialize; use std::alloc::{GlobalAlloc, Layout, System}; use std::cell::Cell; use std::fs::File; use std::hash::{Hash, Hasher}; use std::ops::AddAssign; use std::sync::Mutex; use std::time::{Duration, Instant}; use thousands::Separable; /// A type whose scope dictates the start and end of profiling. /// /// When the first value of this type is dropped, profiling data is written to /// file. Only one value of this type should be created; if subsequent values /// of this type are created they will have no effect. #[derive(Debug)] pub struct Dhat { start_bt: Backtrace, } impl Dhat { /// Initiate allocation profiling. This should be the first thing in /// `main`, and its result should be assigned to a variable whose scope /// ends at the end of `main`. pub fn start_heap_profiling() -> Self { Dhat::start_impl(true) } /// Initiate ad hoc profiling. This should be the first thing in `main`, /// and its result should be assigned to a variable whose scope ends at the /// end of `main`. pub fn start_ad_hoc_profiling() -> Self { Dhat::start_impl(false) } fn start_impl(is_heap: bool) -> Self { if_ignoring_allocs_else( || panic!("start_impl"), || { let tri: &mut Tri<Globals> = &mut TRI_GLOBALS.lock().unwrap(); if let Tri::Pre = tri { let h = if is_heap { Some(HeapGlobals::new()) } else { None }; *tri = Tri::During(Globals::new(h)); } else { eprintln!("dhat: error: A second `Dhat` object was initialized"); } let start_bt = Backtrace(backtrace::Backtrace::new_unresolved()); Dhat { start_bt } }, ) } } impl Drop for Dhat { fn drop(&mut self) { finish(self); } } /// A global allocator that tracks allocations and deallocations on behalf of /// the `Dhat` type. #[derive(Debug)] pub struct DhatAlloc; unsafe impl GlobalAlloc for DhatAlloc { unsafe fn alloc(&self, layout: Layout) -> *mut u8 { if_ignoring_allocs_else( || System.alloc(layout), || { let tri: &mut Tri<Globals> = &mut TRI_GLOBALS.lock().unwrap(); let ptr = System.alloc(layout); if ptr.is_null() { return ptr; } if let Tri::During(g @ Globals { heap: Some(_), .. }) = tri { let size = layout.size(); let bt = Backtrace(backtrace::Backtrace::new_unresolved()); // Get the PpInfo for this backtrace, creating it if // necessary. let pp_info_idx = g.get_pp_info(bt, PpInfo::new_heap); // Record the block. let now = Instant::now(); let h = g.heap.as_mut().unwrap(); let old = h.live_blocks.insert( ptr as usize, LiveBlock { pp_info_idx, allocation_instant: now, }, ); assert!(matches!(old, None)); // Update counts. g.pp_infos[pp_info_idx].update_counts_for_alloc(size); g.update_counts_for_alloc(size, now); } ptr }, ) } unsafe fn realloc(&self, old_ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { if_ignoring_allocs_else( || System.realloc(old_ptr, layout, new_size), || { let tri: &mut Tri<Globals> = &mut TRI_GLOBALS.lock().unwrap(); let new_ptr = System.realloc(old_ptr, layout, new_size); if new_ptr.is_null() { return new_ptr; } if let Tri::During(g @ Globals { heap: Some(_), .. }) = tri { let old_size = layout.size(); let delta = Delta::new(old_size, new_size); if delta.shrinking { // Total bytes is coming down from a possible peak. g.check_for_global_peak(); } // Remove the record of the existing live block and get the // `PpInfo` (which must be present, because we created it // if necessary when this block was allocated.) let h = g.heap.as_mut().unwrap(); let LiveBlock { pp_info_idx, allocation_instant: _, } = h.live_blocks.remove(&(old_ptr as usize)).unwrap(); // Record the new position of the block. let now = Instant::now(); let old = h.live_blocks.insert( new_ptr as usize, LiveBlock { pp_info_idx, allocation_instant: now, }, ); assert!(matches!(old, None)); // Update counts. g.pp_infos[pp_info_idx].update_counts_for_realloc(new_size, delta); g.update_counts_for_realloc(new_size, delta, now); } new_ptr }, ) } unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) { if_ignoring_allocs_else( || System.dealloc(ptr, layout), || { let tri: &mut Tri<Globals> = &mut TRI_GLOBALS.lock().unwrap(); System.dealloc(ptr, layout); if let Tri::During(g @ Globals { heap: Some(_), .. }) = tri { let size = layout.size(); // Remove the record of the live block and get the PpInfo. // (If it's not in the live block table, it must have been // allocated before `TRI_GLOBALS` was set up.) let h = g.heap.as_mut().unwrap(); if let Some(LiveBlock { pp_info_idx, allocation_instant, }) = h.live_blocks.remove(&(ptr as usize)) { // Total bytes is coming down from a possible peak. g.check_for_global_peak(); // Update counts. let alloc_duration = allocation_instant.elapsed(); g.pp_infos[pp_info_idx].update_counts_for_dealloc(size, alloc_duration); g.update_counts_for_dealloc(size); } } }, ); } } /// Register an event during ad hoc profiling. Has no effect unless a `Dhat` /// value that was created with `Dhat::start_ad_hoc_profiling` is in scope. The /// meaning of the weight argument is determined by the user. pub fn ad_hoc_event(weight: usize) { if_ignoring_allocs_else( || panic!("ad_hoc_event"), || { let tri: &mut Tri<Globals> = &mut TRI_GLOBALS.lock().unwrap(); if let Tri::During(g @ Globals { heap: None, .. }) = tri { let bt = Backtrace(backtrace::Backtrace::new_unresolved()); let pp_info_idx = g.get_pp_info(bt, PpInfo::new_ad_hoc); // Update counts. g.pp_infos[pp_info_idx].update_counts_for_ad_hoc_event(weight); g.update_counts_for_ad_hoc_event(weight); } }, ); } // Finish tracking allocations and deallocations, print a summary message // to `stderr` and write output to `dhat-alloc.json`. If called more than // once, the second and subsequent calls will print an error message to // `stderr` and return `Ok(())`. // // Note: this is only separate from `drop` for testing purposes. If // `TRI_GLOBALS` is `Tri::During(g)` on entry then the return value will be // `Some(g)`, otherwise it will be `None`. fn finish(dhat: &mut Dhat) -> Option<Globals> { let mut filename = None; let r: std::io::Result<Option<Globals>> = if_ignoring_allocs_else( || panic!("finish"), || { let tri: &mut Tri<Globals> = &mut TRI_GLOBALS.lock().unwrap(); let tri = std::mem::replace(tri, Tri::Post); let mut g = if let Tri::During(g) = tri { g } else { // Don't print an error message because `Dhat::new` will have // already printed one. return Ok(None); }; let now = Instant::now(); if g.heap.is_some() { // Total bytes is at a possible peak. g.check_for_global_peak(); let h = g.heap.as_ref().unwrap(); // Account for the lifetimes of all remaining live blocks. for &LiveBlock { pp_info_idx, allocation_instant, } in h.live_blocks.values() { g.pp_infos[pp_info_idx] .heap .as_mut() .unwrap() .total_lifetimes_duration += now.duration_since(allocation_instant); } } // We give each unique frame an index into `ftbl`, starting with 0 // for the special frame "[root]". let mut ftbl_indices: FxHashMap<String, usize> = FxHashMap::default(); ftbl_indices.insert("[root]".to_string(), 0); let mut next_ftbl_idx = 1; // Because `g` is being consumed, we can consume `g.backtraces` and // replace it with an empty `FxHashMap`. (This is necessary because // we modify the *keys* here with `resolve`, which isn't allowed // with a non-consuming iterator.) let pps: Vec<_> = std::mem::take(&mut g.backtraces) .into_iter() .map(|(mut bt, pp_info_idx)| { // Do the potentially expensive debug info lookups to get // symbol names, line numbers, etc. bt.0.resolve(); let first_symbol_to_show = first_symbol_to_show(&bt); let last_frame_ip_to_show = last_frame_ip_to_show(&bt, &dhat.start_bt); // Determine the frame indices for this backtrace. This // involves getting the string for each frame and adding a // new entry to `ftbl_indices` if it hasn't been seen // before. let mut fs = vec![]; let mut i = 0; 'outer: for frame in bt.0.frames().iter() { for symbol in frame.symbols().iter() { i += 1; if (i - 1) < first_symbol_to_show { continue; } let s = format!( // Use `{:#}` rather than `{}` to print the // "alternate" form of the symbol name, which // omits the trailing hash (e.g. // `::ha68e4508a38cc95a`). "{:?}: {:#} ({:#}:{}:{})", frame.ip(), symbol.name().unwrap_or_else(|| SymbolName::new(b"???")), // We have the full path, but that's typically // very long and clogs up the output greatly. // So just use the filename, which is usually // good enough. symbol .filename() .and_then(|path| path.file_name()) .and_then(|file_name| file_name.to_str()) .unwrap_or("???"), symbol.lineno().unwrap_or(0), symbol.colno().unwrap_or(0), ); let &mut ftbl_idx = ftbl_indices.entry(s).or_insert_with(|| { next_ftbl_idx += 1; next_ftbl_idx - 1 }); fs.push(ftbl_idx); if Some(frame.ip()) == last_frame_ip_to_show { break 'outer; } } } PpInfoJson::new(&g.pp_infos[pp_info_idx], fs) }) .collect(); // We pre-allocate `ftbl` with empty strings, and then fill it in. let mut ftbl = vec![String::new(); ftbl_indices.len()]; for (frame, ftbl_idx) in ftbl_indices.into_iter() { ftbl[ftbl_idx] = frame; } let h = g.heap.as_ref(); let is_heap = h.is_some(); let json = DhatJson { dhatFileVersion: 2, mode: if is_heap { "rust-heap" } else { "rust-ad-hoc" }, verb: "Allocated", bklt: is_heap, bkacc: false, bu: if is_heap { None } else { Some("unit") }, bsu: if is_heap { None } else { Some("units") }, bksu: if is_heap { None } else { Some("events") }, tu: "µs", Mtu: "s", tuth: if is_heap { Some(10) } else { None }, cmd: std::env::args().collect::<Vec<_>>().join(" "), pid: std::process::id(), tg: h.map(|h| { h.tgmax_instant .saturating_duration_since(g.start_instant) .as_micros() }), te: now.duration_since(g.start_instant).as_micros(), pps, ftbl, }; eprintln!( "dhat: Total: {} {} in {} {}", g.total_bytes.separate_with_commas(), json.bsu.unwrap_or("bytes"), g.total_blocks.separate_with_commas(), json.bksu.unwrap_or("blocks"), ); if let Some(h) = &g.heap { eprintln!( "dhat: At t-gmax: {} bytes in {} blocks", h.max_bytes.separate_with_commas(), h.max_blocks.separate_with_commas(), ); eprintln!( "dhat: At t-end: {} bytes in {} blocks", h.curr_bytes.separate_with_commas(), h.curr_blocks.separate_with_commas(), ); } // `to_writer` produces JSON that is compact, and // `to_writer_pretty` produces JSON that is readable. Ideally we'd // have something between the two (e.g. 1-space indents instead of // 2-space, no spaces after `:`, `fs` arrays on a single line) more // like what DHAT produces. But in the absence of such an // intermediate option, readability trumps compactness. filename = Some(if g.heap.is_some() { "dhat-heap.json" } else { "dhat-ad-hoc.json" }); let filename = filename.unwrap(); let file = File::create(filename)?; serde_json::to_writer_pretty(&file, &json)?; eprintln!( "dhat: The data in {} is viewable with dhat/dh_view.html", filename ); Ok(Some(g)) }, ); match r { Ok(globals) => globals, Err(e) => { eprintln!( "dhat: error: Writing to {} failed: {}", filename.unwrap(), e ); None } } } // We record info about allocations and deallocations. A wrinkle: the recording // done may trigger additional allocations. We must ignore these because (a) // they're part of `dhat`'s execution, not the original program's execution, // and (b) they would be intercepted and trigger additional allocations, which // would be intercepted and trigger additional allocations, and so on, leading // to infinite loops. // // This function runs `f1` if we are ignoring allocations, and `f2` otherwise. // // WARNING: This function must be used for any code within this crate that can // trigger allocations. fn if_ignoring_allocs_else<F1, F2, R>(f1: F1, f2: F2) -> R where F1: FnOnce() -> R, F2: FnOnce() -> R, { thread_local!(static IGNORE_ALLOCS: Cell<bool> = Cell::new(false)); /// If `F` panics, then `ResetOnDrop` will still reset `IGNORE_ALLOCS` /// so that it can be used again. struct ResetOnDrop; impl Drop for ResetOnDrop { fn drop(&mut self) { IGNORE_ALLOCS.with(|b| b.set(false)); } } if IGNORE_ALLOCS.with(|b| b.replace(true)) { f1() } else { let _reset_on_drop = ResetOnDrop; f2() } } // The top frame symbols in a backtrace vary significantly (depending on build // configuration, platform, and program point) but they typically look // something like this: // - backtrace::backtrace::libunwind::trace // - backtrace::backtrace::trace_unsynchronized // - backtrace::backtrace::trace // - backtrace::capture::Backtrace::create // - backtrace::capture::Backtrace::new_unresolved // - <dhat::DhatAlloc as core::alloc::global::GlobalAlloc>::alloc::{{closure}} // - dhat::if_ignoring_allocs_else::{{closure}} // - std::thread::local::LocalKey<T>::try_with // - std::thread::local::LocalKey<T>::with // - dhat::if_ignoring_allocs_else // - <dhat::DhatAlloc as core::alloc::global::GlobalAlloc>::alloc // - __rg_alloc // - alloc::alloc::alloc // - alloc::alloc::Global::alloc_impl // - <alloc::alloc::Global as core::alloc::AllocRef>::alloc // // Such frames are boring and clog up the output. So we scan backwards for the // first frame that looks like it comes from allocator code or this crate's // code. We keep that frame, but discard everything before it. If we don't find // any such frames, we show from frame 0, i.e. all frames. fn first_symbol_to_show(bt: &Backtrace) -> usize { // Get the symbols into a vector so we can reverse iterate over them. let symbols: Vec<_> = bt.0.frames() .iter() .map(|f| f.symbols().iter()) .flatten() .collect(); for (i, symbol) in symbols.iter().enumerate().rev() { if let Some(s) = symbol.name().map(|name| name.to_string()) { // Examples of symbols that this search will match: // - <dhat::DhatAlloc as core::alloc::global::GlobalAlloc>::alloc // - <alloc::alloc::Global as core::alloc::AllocRef>::{alloc,grow} // - __rg_{alloc,realloc} // - alloc::alloc::{alloc,realloc} // - alloc::alloc::exchange_malloc if s.starts_with("alloc::alloc::") || s.starts_with("<alloc::alloc::") || s.starts_with("dhat::") || s.starts_with("<dhat::") || s.starts_with("__rg_") { return i; } } } 0 } // The bottom frame symbols in a backtrace (those below `main`) are typically // the same, and look something like this: // - core::ops::function::FnOnce::call_once (function.rs:227:5) // - std::sys_common::backtrace::__rust_begin_short_backtrace (backtrace.rs:137:18) // - std::rt::lang_start::{{closure}} (rt.rs:66:18) // - core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &F>::call_once (function.rs:259:13) // - std::panicking::try::do_call (panicking.rs:373:40) // - std::panicking::try (panicking.rs:337:19) // - std::panic::catch_unwind (panic.rs:379:14) // - std::rt::lang_start_internal (rt.rs:51:25) // - std::rt::lang_start (rt.rs:65:5) // - _main (???:0:0) // // Such frames are boring and clog up the output. So we compare the bottom // frames with those obtained when the `Dhat` value was created. Those that // overlap in the two cases are the common, uninteresting ones, and we discard // them. fn last_frame_ip_to_show(bt: &Backtrace, start_bt: &Backtrace) -> Option<*mut std::ffi::c_void> { let bt_frames = bt.0.frames(); let start_bt_frames = start_bt.0.frames(); let (mut i, mut j) = (bt_frames.len() - 1, start_bt_frames.len() - 1); loop { if bt_frames[i].ip() != start_bt_frames[j].ip() { return Some(bt_frames[i].ip()); } if i == 0 || j == 0 { return None; } i -= 1; j -= 1; } } lazy_static! { static ref TRI_GLOBALS: Mutex<Tri<Globals>> = Mutex::new(Tri::Pre); } #[derive(PartialEq)] enum Tri<T> { Pre, During(T), Post, } impl<T> Tri<T> { #[cfg(test)] #[track_caller] fn as_ref_unwrap(&self) -> &T { if let Tri::During(v) = self { &v } else { panic!("bad Tri"); } } } // Global state that can be accessed from any thread and is therefore protected // by a `Mutex`. struct Globals { // When `Globals` is created, which is when `Dhat::start_heap_profiling` or // `Dhat::start_ad_hoc_profiling` is called. start_instant: Instant, // All the `PpInfos` gathered during execution. Elements are never deleted. // Each element is referred to by exactly one `Backtrace` from // `backtraces`, and referred to by any number of live blocks from // `live_blocks`. Storing all the `PpInfos` in a `Vec` is a bit clumsy, but // allows multiple references from `backtraces` and `live_blocks` without // requiring any unsafety, because the references are just indices rather // than `Rc`s or raw pointers or whatever. pp_infos: Vec<PpInfo>, // Each `Backtrace` is associated with a `PpInfo`. The `usize` is an index // into `pp_infos`. Entries are not deleted during execution. backtraces: FxHashMap<Backtrace, usize>, // Counts for the entire run. total_blocks: u64, total_bytes: u64, // Extra things kept when heap profiling. heap: Option<HeapGlobals>, } struct HeapGlobals { // Each live block is associated with a `PpInfo`. Each key is the address // of a live block, and thus actually a `*mut u8`, but we store it as a // `usize` because we never dereference it, and using `*mut u8` leads to // compile errors because raw pointers don't implement `Send`. An element // is deleted when the corresponding allocation is freed. live_blocks: FxHashMap<usize, LiveBlock>, // Current counts. curr_blocks: usize, curr_bytes: usize, // Counts at the global max, i.e. when `curr_bytes` peaks. max_blocks: usize, max_bytes: usize, // Time of the global max. tgmax_instant: Instant, } impl Globals { fn new(heap: Option<HeapGlobals>) -> Self { Self { start_instant: Instant::now(), pp_infos: Vec::default(), backtraces: FxHashMap::default(), total_blocks: 0, total_bytes: 0, heap, } } // Get the PpInfo for this backtrace, creating it if necessary. fn get_pp_info<F: FnOnce() -> PpInfo>(&mut self, bt: Backtrace, new: F) -> usize { let pp_infos = &mut self.pp_infos; *self.backtraces.entry(bt).or_insert_with(|| { let pp_info_idx = pp_infos.len(); pp_infos.push(new()); pp_info_idx }) } fn update_counts_for_alloc(&mut self, size: usize, now: Instant) { self.total_blocks += 1; self.total_bytes += size as u64; let h = self.heap.as_mut().unwrap(); h.curr_blocks += 1; h.curr_bytes += size; // The use of `>=` not `>` means that if there are multiple equal peaks // we record the latest one, like `check_for_global_peak` does. if h.curr_bytes >= h.max_bytes { h.max_blocks = h.curr_blocks; h.max_bytes = h.curr_bytes; h.tgmax_instant = now; } } fn update_counts_for_realloc(&mut self, new_size: usize, delta: Delta, now: Instant) { self.total_blocks += 1; self.total_bytes += new_size as u64; let h = self.heap.as_mut().unwrap(); h.curr_blocks += 0; // unchanged h.curr_bytes += delta; // The use of `>=` not `>` means that if there are multiple equal peaks // we record the latest one, like `check_for_global_peak` does. if h.curr_bytes >= h.max_bytes { h.max_blocks = h.curr_blocks; h.max_bytes = h.curr_bytes; h.tgmax_instant = now; } } fn update_counts_for_dealloc(&mut self, size: usize) { let h = self.heap.as_mut().unwrap(); h.curr_blocks -= 1; h.curr_bytes -= size; } fn update_counts_for_ad_hoc_event(&mut self, weight: usize) { assert!(self.heap.is_none()); self.total_blocks += 1; self.total_bytes += weight as u64; } // If we are at peak memory, update `at_tgmax_{blocks,bytes}` in all // `PpInfo`s. This is somewhat expensive so we avoid calling it on every // allocation; instead we call it upon a deallocation (when we might be // coming down from a global peak) and at termination (when we might be at // a global peak). fn check_for_global_peak(&mut self) { let h = self.heap.as_mut().unwrap(); if h.curr_bytes == h.max_bytes { // It's a peak. (If there are multiple equal peaks we record the // latest one.) Record it in every PpInfo. for pp_info in self.pp_infos.iter_mut() { let h = pp_info.heap.as_mut().unwrap(); h.at_tgmax_blocks = h.curr_blocks; h.at_tgmax_bytes = h.curr_bytes; } } } } impl HeapGlobals { fn new() -> Self { Self { live_blocks: FxHashMap::default(), curr_blocks: 0, curr_bytes: 0, max_blocks: 0, max_bytes: 0, tgmax_instant: Instant::now(), } } } struct PpInfo { // The total number of blocks and bytes allocated by this PP. total_blocks: u64, total_bytes: u64, heap: Option<HeapPpInfo>, } #[derive(Default)] struct HeapPpInfo { // The current number of blocks and bytes allocated by this PP. curr_blocks: usize, curr_bytes: usize, // The number of blocks and bytes at the PP max, i.e. when this PP's // `curr_bytes` peaks. max_blocks: usize, max_bytes: usize, // The number of blocks and bytes at the global max, i.e. when // `Globals::curr_bytes` peaks. at_tgmax_blocks: usize, at_tgmax_bytes: usize, // Total lifetimes of all blocks allocated by this PP. Includes blocks // explicitly freed and blocks implicitly freed at termination. total_lifetimes_duration: Duration, } impl PpInfo { fn new_heap() -> Self { Self { total_blocks: 0, total_bytes: 0, heap: Some(HeapPpInfo::default()), } } fn new_ad_hoc() -> Self { Self { total_blocks: 0, total_bytes: 0, heap: None, } } fn update_counts_for_alloc(&mut self, size: usize) { self.total_blocks += 1; self.total_bytes += size as u64; let h = self.heap.as_mut().unwrap(); h.curr_blocks += 1; h.curr_bytes += size; // The use of `>=` not `>` means that if there are multiple equal peaks // we record the latest one, like `check_for_global_peak` does. if h.curr_bytes >= h.max_bytes { h.max_blocks = h.curr_blocks; h.max_bytes = h.curr_bytes; } } fn update_counts_for_realloc(&mut self, new_size: usize, delta: Delta) { self.total_blocks += 1; self.total_bytes += new_size as u64; let h = self.heap.as_mut().unwrap(); h.curr_blocks += 0; // unchanged h.curr_bytes += delta; // The use of `>=` not `>` means that if there are multiple equal peaks // we record the latest one, like `check_for_global_peak` does. if h.curr_bytes >= h.max_bytes { h.max_blocks = h.curr_blocks; h.max_bytes = h.curr_bytes; } } fn update_counts_for_dealloc(&mut self, size: usize, alloc_duration: Duration) { let h = self.heap.as_mut().unwrap(); h.curr_blocks -= 1; h.curr_bytes -= size; h.total_lifetimes_duration += alloc_duration; } fn update_counts_for_ad_hoc_event(&mut self, weight: usize) { assert!(self.heap.is_none()); self.total_blocks += 1; self.total_bytes += weight as u64; } } // A wrapper for `backtrace::Backtrace` that implements `Eq` and `Hash`, which // only look at the frame IPs. This assumes that any two // `backtrace::Backtrace`s with the same frame IPs are equivalent. #[derive(Debug)] struct Backtrace(backtrace::Backtrace); impl PartialEq for Backtrace { fn eq(&self, other: &Self) -> bool { let mut frames1 = self.0.frames().iter(); let mut frames2 = other.0.frames().iter(); loop { let ip1 = frames1.next().map(|f| f.ip()); let ip2 = frames2.next().map(|f| f.ip()); if ip1 != ip2 { return false; } if ip1 == None { return true; } // Otherwise, continue. } } } impl Eq for Backtrace {} impl Hash for Backtrace { fn hash<H: Hasher>(&self, state: &mut H) { for frame in self.0.frames().iter() { frame.ip().hash(state); } } } struct LiveBlock { // The index of the PpInfo for this block. pp_info_idx: usize, // When the block was allocated. allocation_instant: Instant, } // A Rust representation of DHAT's JSON file format, which is described in // comments in dhat/dh_main.c in Valgrind's source code. // // Building this structure in order to serialize does take up some memory. We // could instead stream the JSON output directly to file ourselves. This would // be more efficient but make the code uglier. #[derive(Serialize)] #[allow(non_snake_case)] struct DhatJson { dhatFileVersion: u32, mode: &'static str, verb: &'static str, bklt: bool, bkacc: bool, #[serde(skip_serializing_if = "Option::is_none")] bu: Option<&'static str>, #[serde(skip_serializing_if = "Option::is_none")] bsu: Option<&'static str>, #[serde(skip_serializing_if = "Option::is_none")] bksu: Option<&'static str>, tu: &'static str, Mtu: &'static str, #[serde(skip_serializing_if = "Option::is_none")] tuth: Option<usize>, cmd: String, pid: u32, #[serde(skip_serializing_if = "Option::is_none")] tg: Option<u128>, te: u128, pps: Vec<PpInfoJson>, ftbl: Vec<String>, } // A Rust representation of a PpInfo within DHAT's JSON file format. #[derive(Serialize)] struct PpInfoJson { // `PpInfo::total_bytes and `PpInfo::total_blocks. tb: u64, tbk: u64, // Derived from `PpInfo::total_lifetimes_duration`. #[serde(skip_serializing_if = "Option::is_none")] tl: Option<u128>, // `PpInfo::max_bytes` and `PpInfo::max_blocks`. #[serde(skip_serializing_if = "Option::is_none")] mb: Option<usize>, #[serde(skip_serializing_if = "Option::is_none")] mbk: Option<usize>, // `PpInfo::at_tgmax_bytes` and `PpInfo::at_tgmax_blocks`. #[serde(skip_serializing_if = "Option::is_none")] gb: Option<usize>, #[serde(skip_serializing_if = "Option::is_none")] gbk: Option<usize>, // `PpInfo::curr_bytes` and `PpInfo::curr_blocks` (at termination, i.e. // "end"). #[serde(skip_serializing_if = "Option::is_none")] eb: Option<usize>, #[serde(skip_serializing_if = "Option::is_none")] ebk: Option<usize>, // Frames. Each element is an index into `ftbl`. fs: Vec<usize>, } impl PpInfoJson { fn new(pp_info: &PpInfo, fs: Vec<usize>) -> Self { if let Some(h) = &pp_info.heap { Self { tb: pp_info.total_bytes, tbk: pp_info.total_blocks, tl: Some(h.total_lifetimes_duration.as_micros()), mb: Some(h.max_bytes), mbk: Some(h.max_blocks), gb: Some(h.at_tgmax_bytes), gbk: Some(h.at_tgmax_blocks), eb: Some(h.curr_bytes), ebk: Some(h.curr_blocks), fs, } } else { Self { tb: pp_info.total_bytes, tbk: pp_info.total_blocks, tl: None, mb: None, mbk: None, gb: None, gbk: None, eb: None, ebk: None, fs, } } } } // A change in size. Used for `realloc`. #[derive(Clone, Copy)] struct Delta { shrinking: bool, size: usize, } impl Delta { fn new(old_size: usize, new_size: usize) -> Delta { if new_size < old_size { Delta { shrinking: true, size: old_size - new_size, } } else { Delta { shrinking: false, size: new_size - old_size, } } } } impl AddAssign<Delta> for usize { fn add_assign(&mut self, rhs: Delta) { if rhs.shrinking { *self -= rhs.size; } else { *self += rhs.size; } } } impl AddAssign<Delta> for u64 { fn add_assign(&mut self, rhs: Delta) { if rhs.shrinking { *self -= rhs.size as u64; } else { *self += rhs.size as u64; } } } #[cfg(test)] mod tests;