-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Mark,
On 2/3/2010 11:46 PM, Mark Eggers wrote: > From the taroon-list: If you're running a 32 bit Linux and run out of > low memory, it doesn't matter how much high memory you have, the OOM > killer will start killing processes off. Since you're running a 64 > bit Linux, this should not be the problem. I'm not sure what "low memory" space you're talking about. I don't believe Linux segments memory in any particular way. > A discussion on stackoverflow.com may be more relevant to your > situation. It turns out (according to the discussion) that calling > Runtime.getRuntime().exec() on a busy system can lead to transient > memory shortages which trigger the OOM killer. There is a kernel (ha) of truth to this: *NIX "exec" is implemented as fork() and then exec(), with the former being a "clone this process" call and the latter being a "replace this process with a new one" call. The fork() then duplicates the currently-running process (the JVM) which requires double the memory, and could cause OOM if you have a JVM memory footprint that was close to the logical memory limit that the kernel has imposed. ...except that Linux, specifically, and I would imagine *NIX in general, implements copy-on-write behavior for fork()d processes. That means that calling fork() on a running JVM doesn't eat up that much memory. This is done intentionally because fork() is almost always followed by exec(), where a duplicate of the old process in total would be a big waste of time. Finally, the Linux OOM Killer is likely to choose the /new/ process to murder, since it has been the shortest-running of the two (see http://linux-mm.org/OOM_Killer). On the other hand, if the JVM is doing a /lot/ of Runtime.exec() calls, it's "badness" might be calculated to be quite high, and therefore the process dies. - -chris -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAktrSwMACgkQ9CaO5/Lv0PDZ9QCgwmqz82xDYE/PYPYt3eiRCJ6k cFUAoK5yiUjvTQmICRbzdowihEuG1RWK =L8sd -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
