Tcl_DetachPids(3) Tcl Library Procedures Tcl_DetachPids(3)_________________________________________________________________NAME
Tcl_DetachPids, Tcl_ReapDetachedProcs - manage child pro-
cesses in background
SYNOPSIS
#include <tcl.h>
Tcl_DetachPids(numPids, pidPtr)
Tcl_ReapDetachedProcs()ARGUMENTS
int numPids (in) Number of process ids con-
tained in the array pointed
to by pidPtr.
int *pidPtr (in) Address of array containing
numPids process ids.
_________________________________________________________________DESCRIPTIONTcl_DetachPids and Tcl_ReapDetachedProcs provide a mecha-
nism for managing subprocesses that are running in back-
ground. These procedures are needed because the parent of
a process must eventually invoke the waitpid kernel call
(or one of a few other similar kernel calls) to wait for
the child to exit. Until the parent waits for the child,
the child's state cannot be completely reclaimed by the
system. If a parent continually creates children and
doesn't wait on them, the system's process table will
eventually overflow, even if all the children have exited.
Tcl_DetachPids may be called to ask Tcl to take responsi-
bility for one or more processes whose process ids are
contained in the pidPtr array passed as argument. The
caller presumably has started these processes running in
background and doesn't want to have to deal with them
again.
Tcl_ReapDetachedProcs invokes the waitpid kernel call on
each of the background processes so that its state can be
cleaned up if it has exited. If the process hasn't exited
yet, Tcl_ReapDetachedProcs doesn't wait for it to exit;
it will check again the next time it is invoked. Tcl
automatically calls Tcl_ReapDetachedProcs each time the
exec command is executed, so in most cases it isn't neces-
sary for any code outside of Tcl to invoke Tcl_ReapDe-
tachedProcs. However, if you call Tcl_DetachPids in situ-
ations where the exec command may never get executed, you
may wish to call Tcl_ReapDetachedProcs from time to time
so that background processes can be cleaned up.
Tcl 1
Tcl_DetachPids(3) Tcl Library Procedures Tcl_DetachPids(3)KEYWORDS
background, child, detach, process, wait
Tcl 2