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ERROR_TOO_MANY_SEM_REQUESTS
What ERROR_TOO_MANY_SEM_REQUESTS means
The semaphore cannot be set again because the permitted request or recursion count has been exceeded. The code indicates an invalid repeated operation on a semaphore rather than global resource exhaustion. It is frequently a sign that acquisition and release accounting has become unbalanced.
Common causes
- The same logical request posts or sets the semaphore more than once
- A retry path repeats the state transition after the first attempt succeeded
- Multiple callbacks complete the same operation
- The chosen semaphore type does not support the recursion pattern implemented by the caller
How to investigate
- Assign an identifier to each logical operation and count all set or post attempts
- Check whether timeout and completion callbacks can both execute
- Verify the initial count and maximum count used when the semaphore was created
- Inspect re-entrant code paths that can revisit the same transition
Developer guidance
Make completion idempotent. An atomic state transition should select exactly one winning completion path, and only that path should modify the semaphore.
Administrator and support guidance
The useful evidence is a correlated event sequence showing duplicate posts. System-wide semaphore tuning will not repair application-level double completion.
How this code differs from related results
ERROR_TOO_MANY_SEMAPHORES concerns creating objects; this code concerns too many requests against an existing semaphore.
Evidence worth collecting
For ERROR_TOO_MANY_SEM_REQUESTS, begin the trace at the operation where the same logical request posts or sets the semaphore more than once. Preserve the exact API boundary, numeric result, process and thread identifiers, relevant object state, and the component version. The first verification point should be to assign an identifier to each logical operation and count all set or post attempts. This evidence distinguishes the specific this result contract from a later secondary failure.
Recovery and verification
Recovery for it should address the observed condition rather than merely retrying the same call. After the change, reproduce the scenario in which the same logical request posts or sets the semaphore more than once, then confirm that the intended operation completes and that cleanup returns all associated resources. Also verify that the next repeated operation follows the same successful path without increasing the resource class implicated by this result.
When to escalate
Escalate this result with a minimal reproduction focused on the failing synchronization boundary. Include the operating-system build, binary architecture, runtime or compatibility-layer version, the exact input values, and a timestamped trace showing the same logical request posts or sets the semaphore more than once. For the result escalation record, note whether changing concurrency, object lifetime, target process, module set, or endpoint location alters the result.
References
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