EC
TryLockError::WouldBlock
RustINFOCriticalConcurrency

try_lock failed — lock is already held

Quick Answer

Retry later or fall back to lock() for a blocking acquire.

What this means

try_lock() returned Err(TryLockError::WouldBlock) because another thread currently holds the lock.

Why it happens
  1. 1Another thread holds the mutex
  2. 2Contention on a hot lock

Fix

Non-blocking try with fallback

Non-blocking try with fallback
match mutex.try_lock() {
    Ok(g) => process(g),
    Err(std::sync::TryLockError::WouldBlock) => {
        // do other work, try again later
    }
    Err(e) => return Err(e.into()),
}

Why this works

WouldBlock is not an error state; it signals the caller to retry.

Code examples
Blocking alternativerust
let g = mutex.lock()?; // blocks until available
Sources

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