sshd connections unexpectedly close on windows 2012

[Arnon Yaari <arnony at infinidat dot com>]

Hi,
I'm having problems with running sshd on cygwin on Windows Server 2012 Release Candidate.
I installed cygwin and set up sshd, and I am opening ssh connections using a Python script (running Fabric to perform operations on the Windows machine).
However there appears to be a problem with sshd and my connections sometimes get closed unexpectedly.
I looked in the Event Viewer and found the following log:

"The description for Event ID 0 from source sshd cannot be found. Either the component that raises this event is not installed on your local computer or the installation is corrupted. You can install or repair the component on the local computer.

If the event originated on another computer, the display information had to be saved with the event.

The following information was included with the event:

sshd: PID 2860: error: do_exec_pty: fork: Resource temporarily unavailable"

I also looked in the sshd log in c:\cygwin\var\log\sshd and found this error message:

"      5 [main] sshd 180 fhandler_dev_zero::fixup_mmap_after_fork: requested 0xFEF20000 != 0x0 mem alloc base 0x0, state 0x10000, size 1179648, Win32 error 487
   2833 [main] sshd 180 C:\cygwin\usr\sbin\sshd.exe: *** fatal error in forked process - recreate_mmaps_after_fork_failed
   4115 [main] sshd 180 open_stackdumpfile: Dumping stack trace to sshd.exe.stackdump
      2 [main] sshd 2396 fork: child -1 - forked process 180 died unexpectedly, retry 0, exit code 256, errno 11"

It is not easy to debug this problem because it doesn't happen every time I open an ssh connection but only when I open and close multiple connections subsequently using the Python script.
It appears to be random and the script crashes (because of closed connections) at different points every time.
I tried following the FAQ suggestions and some suggestions from other threads but I had no luck:
I tried running rebaseall with 0x77000000 and 0x40000000.
I tried the latest version of cygwin1.dll.
I tried increasing the heap size in the Windows registry.
Restarting the process or using retry loops is not an option because the problem persists.
The same script and setup work fine on Windows 2003, 2008, 2008R2, and Windows 7.
Any idea what might be causing this problem on Windows 2012? Perhaps some memory settings that I'm missing?

Thanks
Arnon

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