Re: java, multithreading, fork() - performance problem on Solaris
Tim Bradshaw <tfb+google@tfeb.org> writes:
On Mar 25, 3:30 pm, bugbear <bugbear@trim_papermule.co.uk_trim> wrote:
Has any body else seen/experienced this, and
has anybody found a solution/workround?
It might be that posix_spawn has different behaviour, though this
seems unlikely to me. Otherwise the obvious thing would be to have a
separate, single-threaded, process which does the forks to which your
huge JVM can talk using some IPC mechanism.
System and posix_spawn both use vfork(); vfork() also needs to
suspend all threads, pretty much by definition.
Note that fork/fork1 are expensive in requiring all page
table entries for the process to be marked "copy on write".
vfork() is generally cheap because it only needs to suspend the
parent (but that is quite different when the parent has 100s
of threads). (While vfork() is documented as not being thread
safe, the restrictions on its use are known and fixed so we
do know how to safely use it in the implementation of system(),
popen() and posix_spawn)
The fork() process creation model and the POSIX threads in a single
address space model don't really work well together and the
combination should be avoided.
Casper
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