Re: Job table full

Re: Job table full

[Peter Stephenson]

Wayne Davison wrote:
> On Wed, May 12, 2004 at 02:40:29PM +0100, Peter Stephenson wrote:
> > A reliable way of reproducing it would help.
> 
> It's pretty easy:
> 
>     zsh -f
>     preexec() { x=`echo hi` }
>     sleep 1 &
>     :              [execute any 20 commands]
> 
> The problem appears to be that, after the job-control run, the value of
> "thisjob" in the preexec() function becomes -1.  This comparison then
> fails due to a signed/unsigned mismatch:
> 
>     if (thisjob >= jobtabsize - 1 && !expandjobtab()) {

Aha.  That's good.

thisjob is allowed to be -1, it simply means there's no valid
current job.  So the-test-that-no-one-understands should simply have
`thisjob != -1' in it, as in other places in the code.

Here is a fix with some other paranoid tests for thisjob when debugging
is turned on.

Index: Src/exec.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/exec.c,v
retrieving revision 1.62
diff -u -r1.62 exec.c
--- Src/exec.c	21 May 2004 11:19:30 -0000	1.62
+++ Src/exec.c	25 May 2004 18:18:06 -0000
@@ -219,7 +219,7 @@
     /*
      * Is anybody willing to explain this test?
      */
-    if (thisjob >= jobtabsize - 1 && !expandjobtab()) {
+    if (thisjob != -1 && thisjob >= jobtabsize - 1 && !expandjobtab()) {
 	zerr("job table full", NULL, 0);
 	return -1;
     }
Index: Src/jobs.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/jobs.c,v
retrieving revision 1.28
diff -u -r1.28 jobs.c
--- Src/jobs.c	2 May 2004 19:55:58 -0000	1.28
+++ Src/jobs.c	25 May 2004 18:18:07 -0000
@@ -904,6 +904,7 @@
     Process pn, *pnlist;
     struct timezone dummy_tz;
 
+    DPUTS(thisjob == -1, "No valid job in addproc.");
     pn = (Process) zshcalloc(sizeof *pn);
     pn->pid = pid;
     if (text)
@@ -1035,6 +1036,7 @@
 waitjobs(void)
 {
     Job jn = jobtab + thisjob;
+    DPUTS(thisjob == -1, "No valid job in waitjobs.");
 
     if (jn->procs || jn->auxprocs)
 	zwaitjob(thisjob, 0);
@@ -1129,6 +1131,7 @@
 {
     Process pn;
 
+    DPUTS(thisjob == -1, "No valid job in spawnjob.");
     /* if we are not in a subshell */
     if (!subsh) {
 	if (curjob == -1 || !(jobtab[curjob].stat & STAT_STOPPED)) {

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 692070


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Re: Job table full

[Wayne Davison]

On Tue, May 25, 2004 at 07:19:24PM +0100, Peter Stephenson wrote:
> So the-test-that-no-one-understands should simply have
> `thisjob != -1' in it, as in other places in the code.

I think it would also be good to change the type of jobtabsize and
maxjob from "size_t" to "int" so that we don't have a bunch of
signed/unsigned comparisons in the code.  Since other job-number
variables are ints, this should be fine.

..wayne..

Re: job table full.

[Peter Stephenson]

Tanaka Akira wrote:
> I found a problem about job table with 3.1.5-pws-25.
> zsh: job table full

Yes, this is what I found, but it's more serious than I realised.  Simply
using the shell for long enough will eventually hang it.  Looks like zsh is
the first shell with a job table leak.  Well, we've had everything else.

-- 
Peter Stephenson <pws@ibmth.df.unipi.it>       Tel: +39 050 844536
WWW:  http://www.ifh.de/~pws/
Dipartimento di Fisica, Via Buonarroti 2, 56127 Pisa, Italy

job table full.

[Tanaka Akira]

I found a problem about job table with 3.1.5-pws-25.

Z(2):akr@is27e1u11% zsh -f
is27e1u11% while :
while> do
while> =echo $[i++]
while> done
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
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25
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29
30
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45
46
zsh: job table full
is27e1u11% =echo $ZSH_VERSION
3.1.5-pws-25
is27e1u11% 

zsh should not overflow the table.
-- 
Tanaka Akira