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Fix high CPU usage in callback thread due to incorrect timespec #782

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Fix high CPU usage in callback thread due to incorrect timespec #782

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e288ba1
Fix high CPU usage in callback thread due to incorrect timespec
k1-801 Mar 29, 2026
fa70328
Update callback timeout
k1-801 Mar 30, 2026
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12 changes: 6 additions & 6 deletions libusb/hid.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1215,16 +1215,16 @@ static void* callback_thread(void* user_data)
{
(void) user_data;

/* 5 msec timeout seems reasonable; don't set too low to avoid high CPU usage */
/* This timeout only affects how much time it takes to stop the thread */
hidapi_timespec ts;
ts.tv_sec = 0;
ts.tv_nsec = 5000000;

hidapi_thread_mutex_lock(&hid_hotplug_context.callback_thread);

/* We stop the thread if by the moment there are no events left in the queue there are no callbacks left */
while (1) {
/* Pretty much any value between 2 and 100 msec timeout seems reasonable; don't set too low to avoid high CPU usage */
/* This timeout only affects how much time it takes to stop the thread if for any reason thread shutdown wasn't triggered by condition varaiable */
hidapi_timespec ts;
hidapi_thread_gettime(&ts);
hidapi_thread_addtime(&ts, 100);

/* Make the tread fall asleep and wait for a condition to wake it up */
hidapi_thread_cond_timedwait(&hid_hotplug_context.callback_thread, &ts);

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