Re^2: memory not freed after perl exits. Solaris.

Am I storing data on /tmp.
I'm not storing data on /tmp but I do send the STDOUT of the programme to a log file on /tmp.
I don't know if the nature of the /tmp filesystem,
$ df -k .

Filesystem kbytes used avail capacity Mounted on

swap 7077352 1652448 5424904 24% /tmp
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Does that mean that it is of type "swap"? Sorry for my ignorance.

and

no ramdisks on this machine

Actually, you do have a ramdisk on the machine. swapfs / tmpfs / ramdisk are functionally the same thing. They will take blocks from your vm system to use for a disk interface to the system.

Is the size of the logfile in your /tmp filesystem the same as the amount of memory that you are seeing your system go down by?

--MidLifeXis

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Re^3: memory not freed after perl exits. Solaris. by Workplane (Novice) on Nov 25, 2010 at 10:39 UTC
so what I understand from what you wrote: by sending the log file (STDOUT) to /tmp I am forcing the system to use memory to hold the log file? Is that correct? The log file is often larger than the amount of memory which is no longer free (often larger than the system physcial memory) Log file may be up to 8G Physical Memory = 4G Memory "lost" on one run ~ 300M to 2G But why does the memory stay lost (not free)? What can I do to get it back? Shouldn't it be given back when the programme exits and the log file is written to disk (flushed?). I log in via a Citrix connection over a (relatively) slow link, so I can't have gigabytes spewing out to an xterm. Sending it to a file on /tmp seemed a good way to keep the output for debugging purposes. Would I be better off sending the STDOUT to a file on the NFS? That seems like an odd thing if so!	[reply]
Re^4: memory not freed after perl exits. Solaris. by afoken (Chancellor) on Nov 25, 2010 at 12:49 UTC
so what I understand from what you wrote: by sending the log file (STDOUT) to /tmp I am forcing the system to use memory to hold the log file? Is that correct? Yes The log file is often larger than the amount of memory which is no longer free (often larger than the system physcial memory) Log file may be up to 8G Physical Memory = 4G This should make your machine swap like mad. I don't know Solaris that well, on Linux, top and /proc/swaps tell me how much swap is used. I would bet that swap usage is about as large as your log file on /tmp. Memory "lost" on one run ~ 300M to 2G That would match a machine that has stuffed most of the file written to swap, keeping only the most recently used blocks (i.e. the last few mega/giga bytes) in RAM. But why does the memory stay lost (not free)? Because you don't delete the logfile? What can I do to get it back? Delete the logfile from /tmp. Shouldn't it be given back when the programme exits and the log file is written to disk (flushed?). There is no disk behind /tmp. (Well, there is one, if you count the swap partition, but not in the way there is a disk behind /usr or /var.) The swap filesystem is essentially a ramdisk that can overflow into the swap disk, so you can allocate nearly all of your physical RAM plus nearly all of your swap space for temporary data. I log in via a Citrix connection over a (relatively) slow link, so I can't have gigabytes spewing out to an xterm. Sending it to a file on /tmp seemed a good way to keep the output for debugging purposes. Write to a real disk local to the machine you are working on. Ask your admins for a reasonable space. /var/tmp should be a world-writeable directory configured to survive a reboot (i.e. on a disk- or flash-based filesystem) and to be machine-specific (i.e. local disk / flash). Would I be better off sending the STDOUT to a file on the NFS? That seems like an odd thing if so! NFS would put some load on the network, and it is way slower than a local disk or a ramdisk. Think about a less verbose log. Try to filter the log on the fly. Something like: `perl yourscript.pl -foo bar \| grep 'Important' > log.txt` or `perl yourscript.pl -foo bar \| grep -v 'Notice' > log.txt` or `perl yourscript.pl -foo bar \| grep -v 'irrelevant' \| grep -v 'useless' \| grep -v 'crap' > log.txt` Alexander -- Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)	[reply] [d/l] [select]