Make CLOCK_MONOTONIC handling more precise in pal_threading.c #50441
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The root cause of the problem in dotnet#50388 turned out to be because we do not have `pthread_condattr_setclock(..., CLOCK_MONOTONIC);` on iOS. This caused the timeout argument for `pthread_cond_timedwait` to be interpreted as an _absolute system time_ (in seconds since the Unix epoch), however the value we got back from `clock_gettime(CLOCK_MONOTONIC, ...)` was actually some value based on the uptime of the system. Since the uptime is much smaller than the system time the wait immediately returned. Harden the handling by adding a check for `HAVE_PTHREAD_CONDATTR_SETCLOCK` like we already do in `SystemNative_LowLevelMonitor_Create()`
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CoffeeFlux
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Mar 30, 2021
steveisok
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Mar 30, 2021
stephentoub
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Mar 30, 2021
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/backport to release/6.0-preview3 |
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Started backporting to release/6.0-preview3: https://github.com/dotnet/runtime/actions/runs/705796245 |
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The root cause of the problem in #50388 turned out to be because we do not have
pthread_condattr_setclock(..., CLOCK_MONOTONIC);on iOS.This caused the timeout argument for
pthread_cond_timedwaitto be interpreted as an absolute system time (in seconds since the Unix epoch), however the value we got back fromclock_gettime(CLOCK_MONOTONIC, ...)was actually some value based on the uptime of the system.Since the uptime is much smaller than the system time the wait immediately returned.
Harden the handling by adding a check for
HAVE_PTHREAD_CONDATTR_SETCLOCKlike we already do inSystemNative_LowLevelMonitor_Create()