python runtime_error ai_generated true

ValueError: Semaphore acquired too many times

ID: python/asyncio-semaphore-acquire-error

Also available as: JSON · Markdown · 中文
80%Fix Rate
85%Confidence
0Evidence
2025-02-14First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
3.8 active — — —
3.9 active — — —

Root Cause

An asyncio.Semaphore is released more times than it was acquired, causing the counter to exceed the initial value.

generic

中文

asyncio.Semaphore 的释放次数多于获取次数，导致计数器超过初始值。

Workarounds

  1. 95% success Use async with for semaphore to ensure balanced acquire/release 
    async with semaphore:
    # limited resource access
  2. 90% success Track acquire count manually to avoid double release 
    acquired = False
try:
    await semaphore.acquire()
    acquired = True
    # use resource
finally:
    if acquired:
        semaphore.release()

Dead Ends

Common approaches that don't work:

  1. Increasing the semaphore limit to avoid the error 40% fail

    This masks the imbalance bug and may lead to resource exhaustion.

  2. Using a try-finally block that releases unconditionally 60% fail

    If the semaphore was not acquired due to an exception, releasing it causes the error.