Some new data regarding "fork: resource temporarily unavailable"

[Volker Quetschke]

David Arnstein wrote:
> Synopsis:
> the "fork: resource temporarily unavailable" problem may be caused
> by a large number of obsolete process handles.
> 
> Attached to this e-mail:
> 1.  cygcheck.out:
> the output from "cygcheck -s -v -r"
> 2.  tempor.sh:
> A bash shell script that causes the "fork: resource temporarily
> unavailable" problem on my computer. This script searches for
> identical files by brute force: it launches cmp.exe many times.
> 
> First, I ran the standard Windows Task Manager with a non-standard
> column shown: handle count. I noticed something disturbing
> immediately. There is a process (pseudo process?) named
> "System." What I see on my computer is that for this process,
> the handle count rises slowly but continuously. This occurs when
> my computer is almost idle (I have several daemon type processes
> running, so the machine is never completely idle). If I launch any
> program, the handle count jumps up. After terminating the program,
> the handle count does NOT reduce.

First of all, on this Win2k SP4 I don't see that behavior. Even when I start
several "normal" Windows programs that value doesn't increase. (It's at 132
here.)

> Next, I launched "Process Explorer" which is distributed from
> http://www.sysinternals.com. This program allows me to examine the
> handles owned by the "System" process. What I found is that most of
> the handles are Process handles. These handles have names of the form
>     <Non-existent Process> (nnnn)
> where nnnn is a three to five digit number.
I don't have them installed.

> Finally, I ran the attached shell script "tempor.sh." Specifically, I
> opened a Cygwin command window and, at the bash shell prompt, I typed
>     cd C:/Windows/System32
>     tempor.sh *
> 
> This caused tempor.sh to process 2,302 files. This in turn caused
> tempor.sh to launch cmp.exe more than 2.5 million times.

q@lisi /cygdrive/c/WINNT/system32
$ ~/tempor.sh *
Will process 1858 files...

> When tempor.sh started, the number of handles owned by the "System"
> process was less than 10,000.  While tempor.sh was running, I
> watched the status of the "System" process in the Windows Task
> Manager. As expected, I saw the "handles" count for this process
> rise continuously and rather quickly: very roughly, 30 units per
> second. My computer's CPU was 50% to 75% busy at the time.
No, no change in the handles value here. Constantly at 132.

> After many minutes, tempor.sh halted itself with the by-now familiar
> message "fork: resource temporarily unavailable." The number of
> handles owned by the "System" process was about 86,000.
> 
> It appears that Windows itself has a problem clearing out old
> Process handles from some operating system table. It looks like a
> problem not specific to Cygwin at all.  I admit that the evidence
> I present is not conclusive. Nevertheless, the fact that there is
> a boundlessly increasing allocation of a resource (process handles)
> looks suspiciously like breakage to me.
> 
> Would someone please suggest a forum (or book) where I can pursue
> this further. I would like to try to clear out the old handles,
> the ones with names like
>     <Non-existent Process> (nnnn)
> as referenced in "Process Explorer."

I usually hate the WFM messages, but I thought I mention it anyway ;)

> Thank you for any suggestions!

Try a current snapshot. That propably won't help for your problem but
who knows?

   Volker

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