Re: Redhat httpsd with mod_perl
just a followup: i recompiled perl from the redhat source rpms and it seems to have fixed my memory leaks. thanks to everyone for their help remi. Remi Fasol wrote: hi there. i'm having problems with my redhat secure server and mod_perl combo (mod_perl as a DSO). i'm new to mod_perl (and system administration) but obviously am looking forward to getting everything figured out. i believe there is some kind of memory leak (not sure exactly), but when i start the server a typical process has the following characteristics: PID USER PRI NI SIZE RSS SHARE STAT LIB %CPU %MEM TIME COMMAND 6143 nobody 2 0 10720 10M 10072 S 0 0.0 4.1 0:00 httpsd but after running it for about a day (while hitting it with 20 page requests per minute (pages use Apache::ASP and mysql) top shows: PID USER PRI NI SIZE RSS SHARE STAT LIB %CPU %MEM TIME COMMAND 4722 nobody 0 0 18232 14M 3148 S 0 0.0 5.5 0:25 httpsd also, at this point the 'Requests per second' and 'Transfer rate' (as told by ApacheBench) have dropped off significantly. can someone point me in the right direction for optimizing this setup? thanks! remi = __ Do You Yahoo!? Bid and sell for free at http://auctions.yahoo.com
Re: Redhat httpsd with mod_perl
Stas Bekman wrote: Is it a single script/handler you are testing with? *all* children at once? You mean you do a single request and it happens? The only reason I can think of is parent dirtying its memory pages, however I cannot think about a possible way to do this... Yes, I reload VMonitor once, the disk drive chugs for a second, and then *all* children drop to under 3M shared. I think the parent process must have been swapped to disk. It only happens on my home computer (i.e no network traffic), and only after a while of inactivity. And the disk always chugs for a sec right before it happens. Sorry for bothering you with this.. I feel sheepish now that it looks like just a disk swap issue. Is it normal for mod_perl apache processes to forget their shared memory when they come out of swap? - Adi
Re: Redhat httpsd with mod_perl
Randy, Thanks so much for the tips. I got Apache::VMonitor - awesome package, Stas - and investigated it further. What I found was that each child loses a small amount of shared memory during normal use, due to copy-on-write. In my case from about 12M to 9M (roughly 25%). But it stabilizes at 9M shared, and then all of a sudden *all* of the child processes + the parent drop to 3M shared. All of them at once. Could this be due to swapping? (my site is currently very low traffic) I did notice that I could not actively cause the shared memory to dip below 9M. I had to wait a few minutes, and reload VMonitor after a period of no activity. I couldn't test exiting the Apache child, since it isn't a gradual dropoff. BTW, how do you terminate an Apache child process from within mod_perl? Thanks, - Adi Randy Harmon wrote: On Wed, Oct 20, 1999 at 10:47:02PM -0700, Adi wrote: On Wed, 20 Oct 1999, Remi Fasol wrote: Does anyone know why the shared memory would decrease so dramatically? Perl code and data both live in the data segment. As it is used, any time it writes information into a new chunk of memory, the memory is copied-on-write, becoming not-shared. You may or may not benefit from exiting your Apache child when its shared memory size shrinks too much. I think a package of Stas Bekman's authorship may help you detect that occasion. It wraps the gtop library in perl, so you can monitor 'top' info from mod_perl. Your own tests will give you an indication of whether this saves memory and should also indicate whether there is any performance advantage one way or other. It'd be interesting to hear your story of the results. Randy
Re: Redhat httpsd with mod_perl
On Wed, 20 Oct 1999, Remi Fasol wrote: thanks for your suggestions... as a test, i set MaxRequestsPerChild to 500, but it didn't help. just out of curosity, could it be that i'm using mod_perl as a DSO? i've seen alot of warnings against that but that's how the redhat secure server is configured. I'm using redhat secure server also, and I too get the decreasing amount of shared memory as requests are served. However, my SIZE and RSS don't increase like yours do. It looks like a memory leak. Does anyone know why the shared memory would decrease so dramatically? Initially virtually all of the 10M size is shared, then it decreases to about 3M. I'm using Apache::ASP-Loader to pre-load all my .asp scripts, and have all the modules I use pre-loaded into the parent server with PerlModule's. - Adi
Re: Redhat httpsd with mod_perl
On Wed, Oct 20, 1999 at 10:47:02PM -0700, Adi wrote: On Wed, 20 Oct 1999, Remi Fasol wrote: Does anyone know why the shared memory would decrease so dramatically? Perl code and data both live in the data segment. As it is used, any time it writes information into a new chunk of memory, the memory is copied-on-write, becoming not-shared. You may or may not benefit from exiting your Apache child when its shared memory size shrinks too much. I think a package of Stas Bekman's authorship may help you detect that occasion. It wraps the gtop library in perl, so you can monitor 'top' info from mod_perl. Your own tests will give you an indication of whether this saves memory and should also indicate whether there is any performance advantage one way or other. It'd be interesting to hear your story of the results. Randy
Redhat httpsd with mod_perl
hi there. i'm having problems with my redhat secure server and mod_perl combo (mod_perl as a DSO). i'm new to mod_perl (and system administration) but obviously am looking forward to getting everything figured out. i believe there is some kind of memory leak (not sure exactly), but when i start the server a typical process has the following characteristics: PID USER PRI NI SIZE RSS SHARE STAT LIB %CPU %MEM TIME COMMAND 6143 nobody 2 0 10720 10M 10072 S 0 0.0 4.1 0:00 httpsd but after running it for about a day (while hitting it with 20 page requests per minute (pages use Apache::ASP and mysql) top shows: PID USER PRI NI SIZE RSS SHARE STAT LIB %CPU %MEM TIME COMMAND 4722 nobody 0 0 18232 14M 3148 S 0 0.0 5.5 0:25 httpsd also, at this point the 'Requests per second' and 'Transfer rate' (as told by ApacheBench) have dropped off significantly. can someone point me in the right direction for optimizing this setup? thanks! remi = __ Do You Yahoo!? Bid and sell for free at http://auctions.yahoo.com
