On Tue, 22 Mar 2022 19:18:07 +0900 Takashi Yano wrote: > On Mon, 21 Mar 2022 11:45:57 -0700 (PDT) > Jeremy Drake wrote: > > This issue was reported to MSYS2 as a hang when trying to build libxml2 in > > a Windows docker container. Another user was able to come up with a > > simple reproducer and a reasonable theory as to why it happens. The msys2 > > issue is https://github.com/msys2/msys2-runtime/issues/77, and I will > > quote the reproducer and analysis here: > > > > I am having the same issue when building mingw. I managed to reduce the > > issue to the following shell script: > > > > #!/bin/sh > > seq 1 99999 > big_file > > eval '$(eval cmd.exe /c "type big_file" | : )' > > > > When running as a normal user this completes immediately, but when run as > > a system service it hangs forever. The issue appears to be that when > > running under the SYSTEM account, the third sh process holds open the read > > end of the pipe. Since cmd has too much output to write all at once, it > > waits until the pipe's buffer has room to write more, but since sh isn't > > actually reading from the pipe, this hangs forever. When running as a > > normal user the read end of the pipe is not kept open, and so cmd.exe gets > > an error when attempting to write and exits immediately. > > > > My suspicion is that this is caused by f79a461 (which keeps the read end > > of the pipe open) and b531d6b (which changes the behavior depending on > > whether or not the program is running as a service). > > Thanks for the report. This is expected problem as mentioned > in b531d6b commit message. However, I could not imagin the > situation that the service has multiple writer for the pipe > and one of them is a non-cygwin app. > > Question is: Does the docker invoke the command using SYSTEM > account? Or is the processes in docker determined as running > as a service?
I confirmed the processes in Windows docker are running as well_known_service_sid. Let me consider a while. -- Takashi Yano <takashi.y...@nifty.ne.jp> -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
