Fix high CPU usage in callback thread due to incorrect timespec#782
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k1-801 wants to merge 1 commit intolibusb:connection-callbackfrom
Open
Fix high CPU usage in callback thread due to incorrect timespec#782k1-801 wants to merge 1 commit intolibusb:connection-callbackfrom
k1-801 wants to merge 1 commit intolibusb:connection-callbackfrom
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Youw
reviewed
Mar 29, 2026
| /* This timeout only affects how much time it takes to stop the thread */ | ||
| hidapi_timespec ts; | ||
| hidapi_thread_gettime(&ts); | ||
| hidapi_thread_addtime(&ts, 5); |
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I'd set it to 1 second - I've been using 1 second in multiple projects, and seems reasonable
5 second to exit the thread (effectively - to quit the application in some cases) seem a bit too much
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Pull request overview
Fixes high CPU usage in the libusb hotplug callback thread by passing an absolute timeout to hidapi_thread_cond_timedwait() (required by the pthread-backed implementation), instead of a relative timespec.
Changes:
- Move timeout computation into the callback loop and build it as
now + 5msviahidapi_thread_gettime()+hidapi_thread_addtime(). - Align the hotplug callback thread’s timed-wait behavior with the existing timed-wait usage elsewhere in
libusb/hid.c.
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@CalcProgrammer1 noticed high CPU usage (50%) on one of the threads when libusb backend is used for hotplug. It was determined that the load was caused by
hidapi_thread_cond_timedwait(), which requires an absolute timespec, while the code passes a relative value. This patch copies how the structure is filled from the other place wherehidapi_thread_cond_timedwait()is uses, which should fix the issue.