Fix cudaErrorLaunchPendingCountExceeded: CDP Launch Queue Full

Overview

cudaErrorLaunchPendingCountExceeded occurs when too many device-side kernel launches are pending.

Error Messages

CUDA error: launch pending count exceeded
cudaErrorLaunchPendingCountExceeded

Common Causes

• •Too many child launches
• •Missing synchronization
• •Launch queue overflow

Solutions

cudaDeviceSetLimit(cudaLimitDevRuntimePendingLaunchCount, 8192);

__global__ void parent() {
    for (int i = 0; i < 100; i++) {
        child<<<1,1>>>();
        if (i % 50 == 49) cudaDeviceSynchronize();  // Periodic sync
    }
}

Prevention Tips

• ✓Periodic sync in CDP
• ✓Limit concurrent launches
• ✓Batch launches

Code Examples

Before (Problematic)

Too many pending.

for (int i = 0; i < 10000; i++) child<<<1,1>>>();  // Queue overflow

After (Fixed)

Periodic sync.

for (int i = 0; i < 10000; i++) {
    child<<<1,1>>>();
    if (i % 100 == 99) cudaDeviceSynchronize();
}

Frequently Asked Questions

Related Errors

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