[Lldb-commits] [lldb] Fix a bug with cancelling "attach -w" after you have run a process previously (PR #65822)

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jimingham wrote:

The way the test works, we run one real process and let it exit.  Then we do "attach -w -n noone_would_use_this_name" because we don't want the second attach attempt to be able to succeed.  lldb should just stay stuck till the interrupt succeeds, there shouldn't be anything other way to get out of this.  It sounds like something else is kicking us out of the attach wait loop on these systems?

Jim



> On Sep 20, 2023, at 2:56 AM, David Spickett ***@***.***> wrote:
> 
> 
> @DavidSpickett commented on this pull request.
> 
> In lldb/test/API/commands/process/attach/TestProcessAttach.py <https://github.com/llvm/llvm-project/pull/65822#discussion_r1331380724>:
> 
> > +            time.sleep(1)
> +            if target.process.state == lldb.eStateAttaching:
> +                break
> +
> +        self.dbg.DispatchInputInterrupt()
> +        self.dbg.DispatchInputInterrupt()
> +
> +        self.out_filehandle.flush()
> +        reader = open(self.stdout_path, "r")
> +        results = reader.readlines()
> +        found_result = False
> +        for line in results:
> +            if "Cancelled async attach" in line:
> +                found_result = True
> +                break
> +        self.assertTrue(found_result, "Found async error in results")
> This fails if results is empty.
> 
> ********************************
> []
> ********************************
> FAIL: LLDB (/home/david.spickett/build-llvm-aarch64/bin/clang-aarch64) :: test_run_then_attach_wait_interrupt (TestProcessAttach.ProcessAttachTestCase)
> <bound method SBProcess.Kill of SBProcess: pid = 0, state = exited, threads = 0, executable = ProcessAttach>: success
> 
> Restore dir to: /home/david.spickett/build-llvm-aarch64
> ======================================================================
> FAIL: test_run_then_attach_wait_interrupt (TestProcessAttach.ProcessAttachTestCase)
> ----------------------------------------------------------------------
> Traceback (most recent call last):
>   File "/home/david.spickett/llvm-project/lldb/test/API/commands/process/attach/TestProcessAttach.py", line 195, in test_run_then_attach_wait_interrupt
>     self.assertTrue(found_result, "Found async error in results")
> AssertionError: False is not True : Found async error in results
> Config=aarch64-/home/david.spickett/build-llvm-aarch64/bin/clang
> ----------------------------------------------------------------------
> When the test works the results contain:
> 
> ********************************
> ['error: attach failed: Cancelled async attach.\n', '\n', '... Interrupted.\n']
> ********************************
> Running it in a loop it took ~40 runs to get a failing one.
> 
> I wonder if that is because the attach happens to finish a lot faster sometimes, so there's no time to cancel it? If that's down to the OS and machine load, I'm not sure how we'd make this predictable.
> 
> The ugly option is to say if the results are empty, pass the test and assume the other 39 runs will check for the bug.
> 
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https://github.com/llvm/llvm-project/pull/65822