-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Tracy,
Nelson, Tracy M. wrote: > | From: Christopher Schultz [mailto:[EMAIL PROTECTED] > | Sent: Wednesday, 14 March, 2007 10:37 > | > | The fact remains that you can't allocate a VM heap bigger than around > | 1750MB on my 32-bit, 2.6 Linux kernel. Why not? > > If, as you stated earlier, you only have 1G of physical and 1G of virtual > memory, then that's probably the limit you're hitting. Perhaps, but the JVM actually refuses to start right away. In my "eat all my memory" tests, I was able to eat around 1.6GB before I brought my machine to a crawl. It took more than a minute for my terminal to respond to a CRTL-C (or perhaps the kernel killed my process for virtual memory exhaustion). That process took at least a minute. Then again, I was allocating my memory in 50MB chunks and then writing to them. Perhaps Sun's JVM on Linux allocates the whole chunk of memory at once (which doesn't do anything on Linux glibc) and then writes to the last page to see that it can be used. That doesn't seem right, so there must be some other voodoo going on here. > Maybe for the sake of experimenting you could use a USB flash > drive for a swap device. Even if it's just 256MB, you should be able to see > if it's a swap space limitation or something more sinister... Not a bad idea, but sadly I don't have USB support available in my kernel. I have a buddy with a 128MB ppc-Linux 2.6 box with 512MB swap and java installed. I had him check, and his bombs (with a jvm panic!) when asking for even 512MB. So, it looks like physical memory and swap also have an effect. I would have expected the JVM to simply attempt to allocate the memory and use it. For instance, "java -Xmx512M -Xms512M -version" bombs on this little box, even though the heap is pretty much never used. The JVM must check to see if the heap request is ever going to be invalid and then simply refuses to start. Not sure how it does that quickly, though. I know that Linux will lie to a process that requests memory and indicate success when it's possible that actually using that memory will fail. - -chris -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFF+Cso9CaO5/Lv0PARAiT/AKCytag1TNFoOkV0oE0cp3HmhrxmWwCcD1fE aKa8QlXjRcQhGCIPdV84Ngo= =eAGf -----END PGP SIGNATURE----- --------------------------------------------------------------------- To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
