Enum PoolError 

pub enum PoolError {
    Crashed {
        status: Option<ExitStatus>,
        cause: CrashCause,
    },
    Timeout {
        timeout: Duration,
    },
    Protocol(Cow<'static, str>),
    Runtime(MontyException),
    Typing(String),
    Exhausted,
    Spawn(String),
    Finished,
    Disconnected {
        context: String,
    },
    Shutdown {
        dump: Option<Vec<u8>>,
    },
}

Why a pool operation failed.

Variants

Crashed

The worker is gone: it died (segfault, abort, external kill, or EOF on its pipes), or it announced a FatalError and exited — which a serving relay also uses to report that it could not start a worker at all. The worker has been discarded; the pool stays usable.

Fields

status: Option<ExitStatus>

Exit status, when the process could be reaped.

cause: CrashCause

How the pool learned of the death, and what it can say about it.

Timeout

The worker was killed after its turn outlived request_timeout (or one of the feed/turn duration backstop deadlines).

Fields

timeout: Duration

The configured timeout that expired.

Protocol(Cow<'static, str>)

The worker violated the wire protocol, or the caller violated the checkout state machine. Worker-originated protocol failures discard the worker; caller misuse leaves it intact — except a turn cancelled mid-flight, where the abandoned worker is discarded too.

Runtime(MontyException)

The sandboxed code raised a Python exception. The worker and its session remain alive and usable — except for the one MemoryError a worker exceeding its memory limit produces, where the worker is already dead and the checkout finished (its distinct message distinguishes it from the interpreter’s own MemoryError).

Typing(String)

Type checking rejected the fed snippet (sessions created with type_check). The worker and session remain alive; the snippet did not run.

Exhausted

No worker became available within checkout_timeout.

Spawn(String)

A worker process could not be spawned.

Finished

The checkout was already finished or its worker already discarded.

Disconnected

The remote worker’s connection dropped without a turn-ending event (WebSocket transport only — the local analogue is Self::Crashed). The sandbox may have died, or the server may have dropped the session by policy (idle/session/turn timeout, capacity); the two are indistinguishable to a client that only learns of the close, so this deliberately says no more than “the connection went away”.

Fields

context: String

What the pool was doing when the disconnect was observed.

Shutdown

The remote server is shutting down and did not run the request — re-running it on a fresh session is safe. dump restores the session via Checkout::restore on a fresh checkout: the session’s ID from a relay that stores sessions, returned only when PoolConfig::auto_resume could not resume it.

Fields

dump: Option<Vec<u8>>

What restores the session; absent when there is nothing to load — no session yet, an ephemeral one, a relay without storage, or a park that failed.

Trait Implementations

impl Debug for PoolError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for PoolError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Error for PoolError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl From<Error> for PoolError

fn from(err: Error) -> Self

Converts to this type from the input type.