5:01 a.m.
Hi all,
i wonder if i can reuse a connection after a fork?
conn = qb_ipcc_connect(..)
cpid = fork();
if (cpid) {
qb_ipcc_sendv_recv(conn, ..)
else {
qb_ipcc_sendv_recv(conn, ..)
}
I guess each process needs its own connection instead?
- Dietmar
3:41 a.m.
On Tue, Mar 15, 2011 at 10:01:05AM +0000, Dietmar Maurer wrote:
Hi all,
i wonder if i can reuse a connection after a fork?
conn = qb_ipcc_connect(..)
cpid = fork();
if (cpid) {
qb_ipcc_sendv_recv(conn, ..)
else {
qb_ipcc_sendv_recv(conn, ..)
}
I guess each process needs its own connection instead?
Yes a connection for each process, both clients sharing one
block of shared mem is't going to work well.
-Angus
- Dietmar
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6:46 a.m.
> i wonder if i can reuse a connection after a fork?
>
> conn = qb_ipcc_connect(..)
> cpid = fork();
> if (cpid) {
> qb_ipcc_sendv_recv(conn, ..)
> else {
> qb_ipcc_sendv_recv(conn, ..)
> }
>
> I guess each process needs its own connection instead?
Yes a connection for each process, both clients sharing one block of shared
mem is't going to work well.
Would it be possible to detect such mistake in qb_ipcc_sendv_recv() (simply check if the
pid has changed)?
Currently above code works without and error, but can lead to strange bugs.
- Dietmar
3:46 p.m.
On Thu, Mar 17, 2011 at 11:46:56AM +0000, Dietmar Maurer wrote:
> > i wonder if i can reuse a connection after a fork?
> >
> > conn = qb_ipcc_connect(..)
> > cpid = fork();
> > if (cpid) {
> > qb_ipcc_sendv_recv(conn, ..)
> > else {
> > qb_ipcc_sendv_recv(conn, ..)
> > }
> >
> > I guess each process needs its own connection instead?
>
> Yes a connection for each process, both clients sharing one block of shared
> mem is't going to work well.
Would it be possible to detect such mistake in qb_ipcc_sendv_recv() (simply check if the
pid has changed)?
Currently above code works without and error, but can lead to strange bugs.
Does getpid() has any perf. penalty? If not then yes.
-Angus
- Dietmar
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1:39 a.m.
Does getpid() has any perf. penalty? If not then yes.
# man getpid
Since glibc version 2.3.4, the glibc wrapper function for getpid()
caches PIDs, so as to avoid additional system calls when a process
calls getpid() repeatedly. Normally this caching is invisible, but its
correct operation relies on support in the wrapper functions for
fork(2), vfork(2), and clone(2): if an application bypasses the glibc
wrappers for these system calls by using syscall(2), then a call to
getpid() in the child will return the wrong value
So I think we can use that.
- Dietmar
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4 comments
2 participants
participants (2)
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Angus Salkeld -
Dietmar Maurer