Messages in this thread | | | Date | Thu, 13 Apr 2006 02:56:08 -0700 | From | Andrew Morton <> | Subject | Re: PROBLEM: pthread-safety bug in write(2) on Linux 2.6.x |
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Dan Bonachea <bonachead@comcast.net> wrote: > > This problem arose in the parallel runtime system for a scientific language > compiler (nearly a million lines of code total - definitely a "real-world" > program) - the example code is merely a pared-down demonstration of the > problem. In parallel scientific computing, it's very common for many threads > to be writing to stdout (usually for monitoring purposes) and it's expected > and normal for output from separate threads to be arbitrarily interleaved, but > it's *not* ok for output to be lost entirely. This is essentially equivalent > to the real-world example you gave of many threads logging to a file.
Interesting - afaik that's the first time this has been hit in a real application.
> We've worked around the problem in Linux 2.6 by adding locking at user-level > around our writes, as you suggest, although this of course penalizes our > performance on kernels that already correctly implement the thread-safety > required by the POSIX spec. In any case it seemed like a problem that we > should report, to be good open-source citizens - especially given that it > appears to be a regression with respect to the Linux 2.4 kernel. How you > choose to handle the report is of course your decision.
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