Re: print() function hang for long time

[soonix]

To me it looks as if the line from print might be hanging in the output buffer. Perhaps try

$| = 1

at the start of your script and see if that helps.

[dengguochen2003]

Hi, soonix, thank you for the comments.

Could you explain more? What output buffer do you mean? A buffer allocated by print() function?

Wired thing is that I monitor the execution of the script through a putty terminal and find it hangs there for a long while on 2/14 and leave it there. When I am back to it on 2/15 I find it still hangs. So I connect to the machine through the console. When I am in the console it resumes suddenly. The machine configuration is: IBM server -> InReach TTY -> terminal.

[vinoth.ree]

Hi dengguochen2003

Read Suffering from Buffering to know more about buffering.

[dengguochen2003]

Hi, everybody, thank you for your attention on this problem. Finally I got the root cause. The reason is that the Linux kernel is configure to use console as standard output. And at the time when the perl is running the serial port is stuck. So the perl script hangs.

[dengguochen2003]

Hi, vinoth.ree, soonix, thank you for pointing out the perl buffer. While this issue might not apply. I execute this script on various machines and it always goes ok. Only on this IBM machine with TTY console configured this problem shows up. So I am confused a lot. What is more, the script resumes when I login console and hit "return" next day.

[dengguochen2003]

Hi, soonix, thanks for monitoring this issue. Will have a try on your idea. One question is whether the buffer can stuck the process. From the time stamp the process hangs on the print() line for more than 20 hours because code line 23 is executed on 2/15 and gives below time stamp in log line 21(2013/02/15 12:33:27).

2013/02/15 12:33:27 2013/02/14 16:50:12:Audit:event(2)::SYSTEM