Mark, thank you for the detail explanation. I am learning :) On 10/19/07, Mark H. Wood <[EMAIL PROTECTED]> wrote: > On Wed, Oct 17, 2007 at 10:11:36AM -0400, Christopher Schultz wrote: > > > Second strange case: > > > When I start tomcat using /opt/tomcat/bin/catalina.sh start, I get 21 > > > processes that running the same command(different PIDs). And my tomcat > > > instance seems to run fine without problem. When I kill one of the > > > process, the rest will go down as well. > > > > You are seeing each thread as a Linux process. This is perfectly fine > > depending on the kernel version (can't remember which ones do what). > > Linux uses processes to model threads, so it's nothing to worry about. > > It's a little more complex than that. > > Linux recognizes this overarching abstraction called a Context of > Execution. Two COEs that have the same virtual address space are what > most people would think of as "threads". A "process" is the set of > all COEs sharing a given virtual address space. Apparently the thing > that 'ps' is looking at is actually a table of COEs, not processes. > > To make things more fun, different versions of 'ps' work differently. > procps v3 by default coalesces all of a process' threads into a single > line, but 'ps -eLf' will show individual threads. IIRC procps v2 > shows individual threads by default, and I don't recall whether it has > the option of coalescing them. For still more fun, procps forked > between v2 and v3, so it's possible you are still getting fresh > updates of procps v2. > > At one point I had one Tomcat running on Red Hat Linux and another > on Gentoo Linux, and one showed a huge number of Tomcat "processes" > while the other showed only one. Switching attention between the two > was, uh, interesting. > > -- > Mark H. Wood, Lead System Programmer [EMAIL PROTECTED] > Typically when a software vendor says that a product is "intuitive" he > means the exact opposite. > > >
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