[PATCH] gdb.python/py-evthreads.exp: fix racy test (PR testsuite/12649)

[PATCH] gdb.python/py-evthreads.exp: fix racy test (PR testsuite/12649)

[Marek Polacek]

This test fails with read1() because after sending "continue&"
the regexp with ".*" at the end didn't eat all that it ought to.
This causes trouble later on.  Thusly fixed by adding the "\r\n$gdb_prompt".
Tested with both read{,1}.  OK?

2011-06-28  Marek Polacek  <mpolacek@redhat.com>

	* gdb.python/py-evthreads.exp: Fix race by adding an anchor to match 
	the whole output.

--- gdb/gdb/testsuite/gdb.python/py-evthreads.exp.mp    2011-06-22 15:14:07.869452151 +0200
+++ gdb/gdb/testsuite/gdb.python/py-evthreads.exp       2011-06-28 16:10:53.157450752 +0200
@@ -86,7 +86,7 @@ gdb_expect {
 send_gdb "continue&\n"
 gdb_expect {
     -re ".*event type: continue.*
-.*thread num: 1.*" {
+.*thread num: 1.*\r\n$gdb_prompt" {
         pass "continue thread 1"
     }   
     timeout {

Re: [PATCH] gdb.python/py-evthreads.exp: fix racy test (PR testsuite/12649)

[Joel Brobecker]

> 2011-06-28  Marek Polacek  <mpolacek@redhat.com>
> 
> 	* gdb.python/py-evthreads.exp: Fix race by adding an anchor to match 
> 	the whole output.

This is an area where I'm not entirely sure, but we usually use
`$gdb_prompt $' as the anchor.

I'm also surprised to see some uses of gdb_expect in gdb.python.
I wonder if we could replace them with uses of gdb_test_multiple
(that would be a separate patch)...

-- 
Joel

Re: [PATCH] gdb.python/py-evthreads.exp: fix racy test (PR testsuite/12649)

[Marek Polacek]

On 06/28/2011 05:51 PM, Joel Brobecker wrote:
> This is an area where I'm not entirely sure, but we usually use
> `$gdb_prompt $' as the anchor.

Actually, it doesn't matter.  That `$' at the end marks end of the
read buffer, not the end of line.

> I'm also surprised to see some uses of gdb_expect in gdb.python.
> I wonder if we could replace them with uses of gdb_test_multiple
> (that would be a separate patch)...

Yeah, I was thinking about this change too.  I'll try it.

	Marek

Re: [PATCH] gdb.python/py-evthreads.exp: fix racy test (PR testsuite/12649)

[Jan Kratochvil]

On Thu, 30 Jun 2011 12:25:44 +0200, Marek Polacek wrote:
> On 06/28/2011 05:51 PM, Joel Brobecker wrote:
> > This is an area where I'm not entirely sure, but we usually use
> > `$gdb_prompt $' as the anchor.
> 
> Actually, it doesn't matter.  That `$' at the end marks end of the
> read buffer, not the end of line.

It is a difference as it requires the end of the read buffer that way.

If GDB outputs some
(gdb) unexpected_result

then (without any read1 hacks) -re "$gdb_prompt $" will FAIL/timeout as it
should while -re "$gdb_prompt " could give a false PASS.

(I do not think it requires a new commit, it is up to you.)


Thanks,
Jan

Re: [PATCH] gdb.python/py-evthreads.exp: fix racy test (PR testsuite/12649)

[Joel Brobecker]

> It is a difference as it requires the end of the read buffer that way.
> 
> If GDB outputs some
> (gdb) unexpected_result
> 
> then (without any read1 hacks) -re "$gdb_prompt $" will FAIL/timeout as it
> should while -re "$gdb_prompt " could give a false PASS.
> 
> (I do not think it requires a new commit, it is up to you.)

Let's fix it. If anything, we should be consistent. I might have
a minute later today, but I don't want to make the change without
running the testcase... So, I won't mind if someone gets to it before
I do.

-- 
Joel

Re: [PATCH] gdb.python/py-evthreads.exp: fix racy test (PR testsuite/12649)

[Marek Polacek]

On 07/06/2011 07:26 PM, Joel Brobecker wrote:
>> It is a difference as it requires the end of the read buffer that way.
>>
>> If GDB outputs some
>> (gdb) unexpected_result
>>
>> then (without any read1 hacks) -re "$gdb_prompt $" will FAIL/timeout as it
>> should while -re "$gdb_prompt " could give a false PASS.
>>
>> (I do not think it requires a new commit, it is up to you.)
> 
> Let's fix it. If anything, we should be consistent. I might have
> a minute later today, but I don't want to make the change without
> running the testcase... So, I won't mind if someone gets to it before
> I do.
> 

Sure.  Shall I commit the patch below?

2011-07-06  Marek Polacek  <mpolacek@redhat.com>

	* gdb.python/py-evthreads.exp: Add missing `$'.

--- gdb/gdb/testsuite/gdb.python/py-evthreads.exp.mp	2011-07-06 19:34:05.210582529 +0200
+++ gdb/gdb/testsuite/gdb.python/py-evthreads.exp	2011-07-06 19:34:14.660516229 +0200
@@ -86,7 +86,7 @@ gdb_expect {
 send_gdb "continue&\n"
 gdb_expect {
     -re ".*event type: continue.*
-.*thread num: 1.*\r\n$gdb_prompt " {
+.*thread num: 1.*\r\n$gdb_prompt $" {
         pass "continue thread 1"
     }
     timeout {

Re: [PATCH] gdb.python/py-evthreads.exp: fix racy test (PR testsuite/12649)

[Jan Kratochvil]

On Wed, 06 Jul 2011 19:42:15 +0200, Marek Polacek wrote:
> 2011-07-06  Marek Polacek  <mpolacek@redhat.com>
> 
> 	* gdb.python/py-evthreads.exp: Add missing `$'.
> 
> Sure.  Shall I commit the patch below?

I find it OK, please check it in as asked by Joel.


Anyway I have finally completed rework of the testcase which I had
TODO-pending for some months so I will update it anywhere after some review
time.
	Re: [patch] Support inferior events in python
	http://sourceware.org/ml/gdb-patches/2011-07/msg00209.html


Thanks,
Jan

Re: [PATCH] gdb.python/py-evthreads.exp: fix racy test (PR testsuite/12649)

[Marek Polacek]

On 07/06/2011 09:42 PM, Jan Kratochvil wrote:
> I find it OK, please check it in as asked by Joel.

It's in:

	http://sourceware.org/ml/gdb-cvs/2011-07/msg00079.html

> Anyway I have finally completed rework of the testcase which I had
> TODO-pending for some months so I will update it anywhere after some review
> time.
> 	Re: [patch] Support inferior events in python
> 	http://sourceware.org/ml/gdb-patches/2011-07/msg00209.html

Cool.

	Marek

Re: [PATCH] gdb.python/py-evthreads.exp: fix racy test (PR testsuite/12649)

[Marek Polacek]

On 06/28/2011 05:51 PM, Joel Brobecker wrote:
> I'm also surprised to see some uses of gdb_expect in gdb.python.
> I wonder if we could replace them with uses of gdb_test_multiple
> (that would be a separate patch)...

Hmm, after a few days of struggling with converting gdb_expect to 
gdb_test_multiple, I don't think that's The Right Thing anymore.
The issue is that with send_gdb+gdb_expect we always get the same
sequence--e.g., at the "next" test case, we get:

next^M
event type: continue^M
thread num: 1^M
[New Thread 0x7ffff7fe5710 (LWP 1364)]^M
event type: continue^M
thread num: 1^M
47        pthread_create (&thread3_id, NULL, thread3, NULL);^M
event type: stop^M
event type: stop^M
(gdb) ^M
Breakpoint 2, thread2 (d=0x0) at ./gdb.python/py-evthreads.c:39^M
39        int count2 = 0;^M 
event type: stop^M
event type: stop^M
stop reason: breakpoint^M
breakpoint number: 2^M
thread num: 2Quitting ...

However, with gdb_test_multiple, we sometimes get:

next^M
event type: continue^M
thread num: 1^M
[New Thread 0x7ffff7fe5710 (LWP 31327)]^M
event type: continue^M
thread num: 1^M
^M
Breakpoint 2, thread2 (d=0x0) at ./gdb.python/py-evthreads.c:39^M
39        int count2 = 0;^M 
event type: stop^M
event type: stop^M
stop reason: breakpointQuitting ...

and some other time (and this fails):

next^M
event type: continue^M
thread num: 1^M
[New Thread 0x7ffff7fe5710 (LWP 31212)]^M
event type: continue^M
thread num: 1^M
47        pthread_create (&thread3_id, NULL, thread3, NULL);^M
event type: stop^M
event type: stop^M
(gdb) FAIL: gdb.python/py-evthreads.exp: reached breakpoint 2
Quitting ...

I don't understand why the gdb_test_multiple is non-deterministics :(.


I thus propose this simple patch to avoid race (basically the same as before, just
one extra space more).  At least, for now.
Tested with read{,1}.  OK to commit?  Thanks.

2011-07-06  Marek Polacek  <mpolacek@redhat.com>

	* gdb.python/py-evthreads.exp: Fix race by adding an anchor to match
	the whole output.

--- gdb/gdb/testsuite/gdb.python/py-evthreads.exp.mp	2011-06-22 15:14:07.869452151 +0200
+++ gdb/gdb/testsuite/gdb.python/py-evthreads.exp	2011-07-06 13:57:08.651591506 +0200
@@ -86,7 +86,7 @@ gdb_expect {
 send_gdb "continue&\n"
 gdb_expect {
     -re ".*event type: continue.*
-.*thread num: 1.*" {
+.*thread num: 1.*\r\n$gdb_prompt " {
         pass "continue thread 1"
     }
     timeout {

Re: [PATCH] gdb.python/py-evthreads.exp: fix racy test (PR testsuite/12649)

[Joel Brobecker]

> I don't understand why the gdb_test_multiple is non-deterministics :(.

Off the top of my head like that, I don't know either. It might
be a question of bad anchoring, maybe? In any case, I really meant
that as a followup patch anyways...

> 2011-07-06  Marek Polacek  <mpolacek@redhat.com>
> 
> 	* gdb.python/py-evthreads.exp: Fix race by adding an anchor to match
> 	the whole output.

This is OK. Thank you.

-- 
Joel

Re: [PATCH] gdb.python/py-evthreads.exp: fix racy test (PR testsuite/12649)

[Marek Polacek]

On 07/06/2011 04:44 PM, Joel Brobecker wrote:
> This is OK. Thank you.

Applied:
	
	http://sourceware.org/ml/gdb-cvs/2011-07/msg00077.html

Thanks,

	Marek