HR timers prevent an itimer from generating EINTR?
From: Mike Heffner
Date: Fri Sep 04 2009 - 17:34:35 EST
Mixing HR timers with itimers occasionally hides an EINTR from a
In my test program I have a High Resolution timer firing every one
second (with SA_RESTART) and I set an itimer (without SA_RESTART) to
fire after three seconds. I then execute a blocking system call (flock
in this case) and expect the three second itimer to interrupt the system
call with EINTR. However, I frequently notice that the itimer will fire
but it will not interrupt the blocking system call. There appears to be
a race between the HR timer firing and the itimer firing. If I offset
the HR timer frequency by a half second, the itimer always interrupts
the system call.
These kernels both demonstrate the condition:
I do not see this condition on:
The following program illustrates this condition:
Is this behavior expected?
Mike Heffner <mikeh@xxxxxxxxxx>
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