Hi All, I'm hitting a problem using os.exec Cmd.Start to run a process.
I'm setting Cmd.Stdio and Cmd.Stderr to the same instance of an io.Pipe, and spawn a Goroutine to consume the pipe reader until I reach EOF. I then call cmd.Start(), do some additional work, and call cmd.Wait(). The runtime of the executable I launch is 15-30 minutes, and stdout/stderr output is minimal, a few 10's of kB during this 15-30 minute run. When the pipe reaches EOF or errors out, I close the pipe reader, exit the goroutine reading the pipe, and that's when cmd.Wait() returns, exactly as documented. This works exactly as described about 70% of the time. The remaining 30% of the time, cmd.Wait() returns an error, which stringifies as "signal: broken pipe". I'm running thousands of copies of this executable across thousands of instances in AWS, so I have a big data set here. The broken pipe error happens at the very end when my exec'd executable is exiting, so as far as I can tell, it's run successfully and is hitting this error on exit. I realize that SIGPIPE and EPIPE are common ways that processes clean each other up, and that shells do a lot of work hiding them, so I've also tried using exec.Cmd to spawn bash, which in turn runs my executable, but I still get a lot of these deaths due to SIGPIPE. I've tried to reproduce this with simple commands - like `cat <longfile.txt>`, and none of these simple commands ever result in the broken pipe, and I capture all their output without issue. The command I'm running differs in that it uses quite a lot of resources and the machine is doing significant work when the executable is exiting. However, the sigpipe is being received by the application, not my Go code, implying that the Go side is closing the pipe. I can't find where this is happening. Any tips on how to chase this down? Thanks, -- Marcin -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CA%2Bv29LtLQDxac3L1_75Bv4_A%2B1AO2w46h%2Bkp8yx4aEw9x5UzcA%40mail.gmail.com.
