> From: Christopher Schultz [mailto:[EMAIL PROTECTED] > Subject: [OT]Re: Is better one or more Tomcat instances per machine
The below applies only to 32-bit systems, of course. > Some claim that 32-bit OSs can't use more than 4GB RAM Lots of people seem to confuse virtual space with real memory. There is a 4GB limitation on virtual space per process (IA32 architecture), but the real memory (RAM) limit depends on the OS and the number of address lines implemented between the CPU and memory, up to the max 64 GB supported by IA32. > that they have 2GB/2GB kernel and process memory boundaries Windows certainly does have such a boundary (although in certain server versions, this can be changed to 3GB/1GB user/kernel). Most other OSs don't have a fixed boundary, but they do have a maximum virtual memory size (set by ulimit in Linux), and each installation can specify a default. > since the Java heap need not be contiguous Wouldn't it be nice if that were true. I haven't looked at the Java SE 6 HotSpot code yet, but in all prior versions of Sun's JVM, the heap was allocated as one contiguous chunk, including the PermGen. HotSpot has the ability to shift the boundaries between generations, and thus requires the heap to be contiguous. Windows makes the situation worse by scattering various DLLs and other allocations throughout the 2GB user process space, thereby significantly reducing the contiguous space available for the JVM heap. - Chuck THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE PROPRIETARY MATERIAL and is thus for use only by the intended recipient. If you received this in error, please contact the sender and delete the e-mail and its attachments from all computers. --------------------------------------------------------------------- To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
