CPU usage jumps to 100% when braking a SSH session

[Mateusz Viste]

Hi,

I noticed that the CPU is jumping to 100% when I quit a SSH session without using the "exit" command (for example, if I simply close the window of my console).

When looking at a TOP, see that the process "-sh" is consuming all the CPU (normally, I would expect that process to be killed when the SSH connection stops).

Even worse: if I log on several times, and quit the SSH console without using "exit", then I see in the TOP several "-sh" processes fighting for the last drop of CPU power...

[devon]

Testing revealed that RC2 (released Fri, 12 Mar 2010) does not exhibit this behavior but RC3 (released Fri, 9 Apr 2010 11:54:22) does.

[devon]

More testing...
Looks like the culprit is busybox, I reverted to 1.14.3 on r1478 and the problem is gone.

[devon]

More testing...Part II
Compiling a fresh 1520 from trunk yielded the same result as RC3 with the cpu usage shooting to 100% after exiting putty by closing the window instead of typing 'exit'.

After upgrading to busybox 1.16.1 in 1520 the problem goes away. I will work on patching touch in the latest version and post the diff.

[Michael]

Touch is already working (the reason to switch to the 1.15.x series). Do you mean patching it back into the 1.14 series? That would maybe be the best option...or to figure out the bug itself and get it patched. I looked through the busybox tracker and found nothing relevant.

[devon]

Touch is working but does not support the -t option unless compiled with DESKTOP enabled (bigger code) .
The patch to touch.c I was suggesting would remove the check for DESKTOP and compile the binary with all supported options.

[Michael]

Doesn't this take care of it? It's been implemented for a awhile now.
 - https://wush.net/trac/askozia/browser/trunk/package/base/busybox/touch_args.patch

I thought I tested this with everything working fine.

[devon]

I thought I tested this with everything working fine.

I agree, everything did seem to be working fine with busybox 1.15.3 until the report of the cpu issue. I've rebuilt r1520 with 1.15.3 without the touch modifications and get the same results, cpu goes 100% when closing putty window. Rebuilt with 1.14.3 and 1.16.1 and saw no cpu usage issues when disconnecting.

@Michael, if you get a chance, could you test the latest build to see if the cpu spikes when closing putty ssh window?

[Michael]

Just tested: it spikes & stays at 100%.

If the touch changes could be rolled into 1.14.3, I will go with that version in the next point release of Askozia. I'd like to move up to 1.16.1 but it's untested. The 1.14.x releases were tested for a long time on all platforms.