On 10/09/2013 06:37 PM, Daniel Merrill wrote:
On 10/09/2013 06:29 PM, Daniel Merrill wrote:
All,
I'm hoping maybe someone can shed a little more light on the issue we
see occasionally. Occasionally our code using the psos+ skin will fail
a
t_suspend(0) with error code -4, which I found to be EINTR and appears
to be set if the XNBREAK flag is set. After digging around in the
documentation I found some references that seem to indicate that this
means the thread was forcibly unblocked for some reason. Is there some
way to diagnose what caused this (I'm having trouble pinpointing
anything)? It appears when debugging that the thread never really
suspends at all but returns immediately from the call. Does anyone
have some pointers on what might be a good place to start looking for
the culprit? Thanks in advance.
Are you tracing the application with GDB?
We are using GDB to diagnose problems, can this cause the issue?
It should not, but one of the reasons for a thread to get forcibly
unblocked is to receive a regular linux signal when blocked in primary
mode. Since GDB does send quite a few signals to the application when
single-stepping/breakpointing the code, this information may be useful
to know. In short, GDB/ptracing might magnify a bug in this area.
If this issue also happens with no ptracing, then some other source
kicked the thread out of wait state, and we'd have to instrument the
code to know who does this.
--
Philippe.
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