[SunHELP] RE: memory leak under Solaris 7

[OFrayman]

> 	The amount of memory you should see is 1/64 th of the amount you
> have.  Here is the article that explains everything that was sent to me
> directly from SUN.  Hope this helps.
> 
> 	Here is the article written by the Guru of Performance at SUN
> 	he wrote the book Sun performance and tuning and descibes what is
> happen to your memory
> 	While the aticle is from 1995 it is still valid today.Is this what
> you need?
> 
> 	SunOS and Solaris handle your precious RAM. October  1995 
> 
> 	Abstract 
> 
> 	    Why doesn't Sun's OS free unused memory? Adrian Cockcroft
> tackles this question in the first of his
> 	    monthly performance columns for SunWorld Online. Cockcroft,
> Sun's performance guru, has heard and
> 	    answered this and countless other questions during his years as
> a systems engineer. Once he explains how
> 	    Solaris 1 and 2 handle your computer's memory, you'll probably
> be relieved. (2,600 words) 
> 
> 
> 
> 	Dear Adrian,
> 	After a reboot I saw that most of my computer's memory was free, but
> when I launched my application
> 	it used up almost all the memory. When I stopped the application the
> memory didn't come back! Take a
> 	look at my vmstat output: 
> 
> 	% vmstat 5
> 	 procs     memory            page            disk          faults
> cpu
> 	 r b w   swap  free  re  mf pi po fr de sr s0 s1 s2 s3   in   sy
> cs us sy id
> 
> 	This is before the program starts:
> 
> 	 0 0 0 330252 80708   0   2  0  0  0  0  0  0  0  0  1   18  107
> 113  0  1 99
> 	 0 0 0 330252 80708   0   0  0  0  0  0  0  0  0  0  0   14   87
> 78  0  0 99
> 
> 	I start the program and it runs like this for a while:
> 
> 	 0 0 0 314204  8824   0   0  0  0  0  0  0  0  0  0  0  414  132
> 79 24  1 74
> 	 0 0 0 314204  8824   0   0  0  0  0  0  0  0  0  0  0  411   99
> 66 25  1 74
> 
> 	I stop it, then almost all the swap space comes back, but the free
> memory does not:
> 
> 	 0 0 0 326776 21260   0   3  0  0  0  0  0  0  1  0  0  420  116
> 82  4  2 95
> 	 0 0 0 329924 24396   0   0  0  0  0  0  0  0  0  0  0  414   82
> 77  0  0 100
> 	 0 0 0 329924 24396   0   0  0  0  0  0  0  0  2  0  1  430   90
> 84  0  1 99
> 
> 	I checked that there were no application processes running. It looks
> like a huge memory leak in the operating
> 	system. How can I get my memory back?
> 	--RAMless in Ripon 
> 
> 	The short answer
> 	Launch your application again. Notice that it starts up more quickly
> than it did the first time, and with less disk
> 	activity. The application code and its data files are still in
> memory, even though they are not active. The memory
> 	they occupy is not "free." If you restart the same application it
> finds the pages that are already in memory. The
> 	pages are attached to the inode cache entries for the files. If you
> start a different application, and there is
> 	insufficient free memory, the kernel will scan for pages that have
> not been touched for a long time, and "free" them.
> 	Once you quit the first application, the memory it occupies is not
> being touched, so it will be freed quickly for use
> 	by other applications. 
> 
> 	In 1988, Sun introduced this feature in SunOS 4.0. It still applies
> to all versions of Solaris 1 and 2. The kernel is
> 	trying to avoid disk reads by caching as many files as possible in
> memory. Attaching to a page in memory is around
> 	1,000 times faster than reading it in from disk. The kernel figures
> that you paid good money for all of that RAM, so
> 	it will try to make good use of it by retaining files you might
> need. 
> 
> 	By contrast, Memory leaks appear as a shortage of swap space after
> the misbehaving program runs for a while. You
> 	will probably find a process that has a larger than expected size.
> You should restart the program to free up the
> 	swap space, and check it with a debugger that offers a leak-finding
> feature (SunSoft's DevPro debugger, for
> 	example). 
> 
> 
> 
> 	Oleg Frayman	
> 	Sun Certified System Administrator
> 	190 W. Germantown Pike, Suite 210
> 	Norristown , PA. 19401-1385
> 	Phone: 610-278-1838 x147  Fax 610-278-6638
> 	mailto:ofrayman at verticalalliance.com
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