[Bug testsuite/31440] New: [gdb/testsuite] FAIL: gdb.python/py-progspace-events.exp: inferior 1 (timeout)

[Bug testsuite/31440] New: [gdb/testsuite] FAIL: gdb.python/py-progspace-events.exp: inferior 1 (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31440

            Bug ID: 31440
           Summary: [gdb/testsuite] FAIL:
                    gdb.python/py-progspace-events.exp: inferior 1
                    (timeout)
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: testsuite
          Assignee: unassigned at sourceware dot org
          Reporter: vries at gcc dot gnu.org
  Target Milestone: ---

On arm-linux I ran into:
...
(gdb) PASS: gdb.python/py-progspace-events.exp: continue until inferior 2 exits
inferior 1^M
[Switching to inferior 1 [process 5199]
(/home/rock/gdb/build/gdb/testsuite/outputs/gdb.python/py-progspace-events/py-progspace-events)]^M
[Switching to thread 1.1 (Thread 0xf77d0ce0 (LWP 5199))]^M
#0  breakpt () at
/home/rock/gdb/src/gdb/testsuite/gdb.python/py-progspace-events.c:28^M
28      { /* Nothing.  */ }^M
(gdb) FreeProgspaceEvent: <gdb.Progspace object at 0xabaf03a0>^M
FAIL: gdb.python/py-progspace-events.exp: inferior 1 (timeout)
...

Looks like a missing no-prompt-anchor.

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[Bug testsuite/31440] [gdb/testsuite] FAIL: gdb.python/py-progspace-events.exp: inferior 1 (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31440

--- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> ---
Reproducible on x86_64:
...
$ for n in $(seq 1 100); do taskset -c 11 ./test.sh 2>&1 | grep "# of " | sort
-u; done
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            11
# of unexpected failures        2
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            12
# of unexpected failures        1
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            12
# of unexpected failures        1
# of expected passes            13
# of expected passes            11
# of unexpected failures        2
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            11
# of unexpected failures        2
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            11
# of unexpected failures        2
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
# of expected passes            13
^C
...

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[Bug gdb/31440] [gdb] FAIL: gdb.python/py-progspace-events.exp: inferior 1 (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31440

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[gdb/testsuite] FAIL:       |[gdb] FAIL:
                   |gdb.python/py-progspace-eve |gdb.python/py-progspace-eve
                   |nts.exp: inferior 1         |nts.exp: inferior 1
                   |(timeout)                   |(timeout)
          Component|testsuite                   |gdb

--- Comment #2 from Tom de Vries <vries at gcc dot gnu.org> ---
Hmm, the test-case says:
...
# Switch to inferior 2 and continue until we hit breakpt.                       
gdb_test "inferior 2" "\\\[Switching to inferior 2 .*"
gdb_continue_to_breakpoint "run to breakpt in inferior 2"

# Let inferior 2 exit.  The new program space is not removed at this            
# point.                                                                        
gdb_test "continue" \
    [multi_line \
         "^Continuing\\." \
         "\\\[Inferior $decimal \[^\r\n\]+ exited normally\\\]"] \
    "continue until inferior 2 exits"

gdb_test "inferior 1" "\\\[Switching to inferior 1 .*"

# Step the inferior.  During this process GDB will prune the now                
# defunct inferior, which deletes its program space, which should               
# trigger the FreeProgspaceEvent.                                               
...

So, it explicitly states that the FreeProgspaceEvent should not happen until
after the step is issued.

At this point I'm not sure if this is indeed a test-case issue.

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[Bug gdb/31440] [gdb] FAIL: gdb.python/py-progspace-events.exp: inferior 1 (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31440

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |aburgess at redhat dot com

--- Comment #3 from Tom de Vries <vries at gcc dot gnu.org> ---
I build gdb at commit 59912fb2d22 ("gdb: add Python events for program space
addition and removal"), which introduced the test-case.

Already there I see the same FAIL, and also this variant which looks slightly
different:
...
(gdb) PASS: gdb.python/py-progspace-events.exp: continue until inferior 2 exits
inferior 1^M
[Switching to inferior 1 [process 24038]
(/data/vries/gdb/leap-15-4/build/gdb/testsuite/outputs/gdb.python/py-progspace-events/py-progspace-events)]^M
[Switching to thread 1.1 (process 24038)]^M
#0  breakpt () at
/data/vries/gdb/src/gdb/testsuite/gdb.python/py-progspace-events.c:28^M
28      { /* Nothing.  */ }^M
(gdb) PASS: gdb.python/py-progspace-events.exp: inferior 1
FreeProgspaceEvent: <gdb.Progspace object at 0x7efcaa520300>^M
step^M
do_parent_stuff () at
/data/vries/gdb/src/gdb/testsuite/gdb.python/py-progspace-events.c:41^M
41        ++global_var;^M
(gdb) FAIL: gdb.python/py-progspace-events.exp: step
...

The test-case seems to fail about 1 out of 4 times.

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[Bug gdb/31440] [gdb] FAIL: gdb.python/py-progspace-events.exp: inferior 1 (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31440

--- Comment #4 from Tom de Vries <vries at gcc dot gnu.org> ---
I wondered about using print in the python script, and tried this patch, but
that doesn't fix it either:
...
diff --git a/gdb/testsuite/gdb.python/py-progspace-events.py
b/gdb/testsuite/gdb.python/py-progspace-events.py
index 23c6fc52f4d..6f41888b65b 100644
--- a/gdb/testsuite/gdb.python/py-progspace-events.py
+++ b/gdb/testsuite/gdb.python/py-progspace-events.py
@@ -21,11 +21,13 @@ import gdb.events


 def new_progspace(event):
-    print("NewProgspaceEvent: %s" % str(event.progspace))
+    gdb.write("NewProgspaceEvent: %s\n" % str(event.progspace))
+    gdb.flush()


 def free_progspace(event):
-    print("FreeProgspaceEvent: %s" % str(event.progspace))
+    gdb.write("FreeProgspaceEvent: %s\n" % str(event.progspace))
+    gdb.flush()


 gdb.events.new_progspace.connect(new_progspace)
...

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[Bug gdb/31440] [gdb] FAIL: gdb.python/py-progspace-events.exp: inferior 1 (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31440

--- Comment #5 from Tom de Vries <vries at gcc dot gnu.org> ---
I added some debug printfs, and got the following output.

Passing case:
...
(gdb) PASS: gdb.python/py-progspace-events.exp: continue to breakpoint: run to
breakpt in inferior 2
continue^M
Continuing.^M
not removable: inf 1^M
not deletable: inf 2^M
[Inferior 2 (process 4549) exited normally]^M
not removable: inf 1^M
not deletable: inf 2^M
(gdb) not removable: inf 1^M
not deletable: inf 2^M
PASS: gdb.python/py-progspace-events.exp: continue until inferior 2 exits
inferior 1^M
[Switching to inferior 1 [process 4546] (py-progspace-events)]^M
[Switching to thread 1.1 (process 4546)]^M
#0  breakpt () at py-progspace-events.c:28^M
28      { /* Nothing.  */ }^M
(gdb) PASS: gdb.python/py-progspace-events.exp: inferior 1
step^M
not deletable: inf 1^M
delete_inferior: inf 2^M
FreeProgspaceEvent: <gdb.Progspace object at 0x7efd1faf0ee0>^M
...

Failing case:
...
(gdb) PASS: gdb.python/py-progspace-events.exp: continue to breakpoint: run to
breakpt in inferior 2
continue^M
Continuing.^M
not removable: inf 1^M
not deletable: inf 2^M
[Inferior 2 (process 4752) exited normally]^M
not removable: inf 1^M
not deletable: inf 2^M
(gdb) PASS: gdb.python/py-progspace-events.exp: continue until inferior 2 exits
inferior 1^M
[Switching to inferior 1 [process 4742] (py-progspace-events)]^M
[Switching to thread 1.1 (process 4742)]^M
#0  breakpt () at py-progspace-events.c:28^M
28      { /* Nothing.  */ }^M
(gdb) not deletable: inf 1^M
delete_inferior: inf 2^M
FreeProgspaceEvent: <gdb.Progspace object at 0x7f3a6faf0ee0>^M
FAIL: gdb.python/py-progspace-events.exp: inferior 1 (timeout)
step^M
...

So, it seems there's a race between some event and the "inferior 1" command.

In the passing case, the event is handled first.  During handling,
prune_inferiors is called, but it can't remove inferior 1, because it's still
the current one.

In the failing case, the "inferior 1" is handled first. Then during handling of
the event, prune_inferiors is called, and it can remove inferior 1 because it's
no longer the current one.

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[Bug gdb/31440] [gdb] FAIL: gdb.python/py-progspace-events.exp: inferior 1 (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31440

--- Comment #6 from Tom de Vries <vries at gcc dot gnu.org> ---
By pruning the inferiors asap:
...
diff --git a/gdb/inferior.c b/gdb/inferior.c
index 5ff5eb98955..9dc34ed72e4 100644
--- a/gdb/inferior.c
+++ b/gdb/inferior.c
@@ -791,6 +791,7 @@ inferior_command (const char *args, int from_tty)
          notify_user_selected_context_changed
            (USER_SELECTED_INFERIOR);
        }
+      prune_inferiors ();
     }
 }

...
we get stable output:
...
(gdb) PASS: gdb.python/py-progspace-events.exp: continue until inferior 2 exits
inferior 1^M
[Switching to inferior 1 [process 5991] (py-progspace-events)]^M
[Switching to thread 1.1 (process 5991)]^M
#0  breakpt () at py-progspace-events.c:28^M
28      { /* Nothing.  */ }^M
FreeProgspaceEvent: <gdb.Progspace object at 0x7f62ca9b0ee0>^M
(gdb) PASS: gdb.python/py-progspace-events.exp: inferior 1
...

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[Bug gdb/31440] [gdb] FAIL: gdb.python/py-progspace-events.exp: inferior 1 (timeout)

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31440

--- Comment #7 from Tom de Vries <vries at gcc dot gnu.org> ---
https://sourceware.org/pipermail/gdb-patches/2024-March/206996.html

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