Fix cudaErrorNotReady: Async Operation Not Complete

Overview

cudaErrorNotReady is returned by cudaStreamQuery or cudaEventQuery when an async operation hasn't completed. This is informational, not an error.

Error Messages

CUDA error: not ready
cudaErrorNotReady: async operation not complete

Common Causes

• •Querying stream before completion
• •Non-blocking event query
• •Async memcpy in progress

Solutions

cudaStreamSynchronize(stream);
// Or
cudaDeviceSynchronize();

while (cudaStreamQuery(stream) == cudaErrorNotReady) {
    // Do other work
}
// Stream complete

Prevention Tips

• ✓Use cudaStreamSynchronize for blocking wait
• ✓NotReady is expected in non-blocking queries

Code Examples

Before (Problematic)

Not handling NotReady case.

cudaStreamQuery(stream);  // May return NotReady
use_results();  // Data may not be ready!

After (Fixed)

Properly handle NotReady.

cudaError_t status = cudaStreamQuery(stream);
if (status == cudaErrorNotReady) {
    // Still running
} else if (status == cudaSuccess) {
    use_results();
}

Frequently Asked Questions

Related Errors

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