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Re: long I/O delays when strace is running




I've tracked it down to this little Sleep() loop in pinfo::init.

      bool created = shloc != SH_JUSTOPEN;

/* Detect situation where a transitional memory block is being retrieved.
     If the block has been allocated with PINFO_REDIR_SIZE but not yet
     updated with a PID_EXECED state then we'll retry. */
      if (!created && !(flag & PID_NEW))
    /* If not populated, wait 2 seconds for procinfo to become populated.
       Would like to wait with finer granularity but that is not easily
       doable.  */
    for (int i = 0; i < 200 && !procinfo->ppid; i++)
      Sleep (10);

I tried putting a stupid memory barrier in the loop and a volatile read just for kicks, but that doesn't seem to be the problem. I'm headed off to bed. This only happens when using strace, so if anybody has ideas please post.

Daniel

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