Re: [PATCH] gdb/testsuite: Increase timeout when using read1 in gdb.base/osabi.exp

[Simon Marchi <simark@simark.ca>]

On 3/1/24 14:27, Thiago Jung Bauermann wrote:
> The Linaro CI runs the GDB testsuite using the read1 tool, which
> significantly increases the time it takes DejaGNU to read inferior output.
> On top of that, sometimes the test machine has higher than normal load,
> which causes tests to run even slower.
> 
> Because the gdb.base/osabi.exp enables "debug arch" output, which is
> somewhat verbose, it sometimes fails when running in the Linaro CI
> environment.
> 
> Fix this problem by using a timeout factor to run the test.
> ---
>  gdb/testsuite/gdb.base/osabi.exp | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/gdb/testsuite/gdb.base/osabi.exp b/gdb/testsuite/gdb.base/osabi.exp
> index 9bbfff52bae8..47d5755f1584 100644
> --- a/gdb/testsuite/gdb.base/osabi.exp
> +++ b/gdb/testsuite/gdb.base/osabi.exp
> @@ -27,4 +27,6 @@ proc test_set_osabi_none { } {
>      gdb_test "set osabi none" ".*gdbarch_find_by_info: info.osabi 1 \\(none\\).*"
>  }
>  
> -test_set_osabi_none
> +with_read1_timeout_factor 10 {
> +    test_set_osabi_none
> +}

Hi Thiago,

If it was really a case of "GDB is thinking for a long time before
spewing out an answer", then I think that increasing the timeout would
be the right fix (or, make GDB faster).

But here, it appears that it's GDB outputting a lot of lines, and
dejagnu taking some time to read it.  I'm actually surprised that
dejagnu times out, since it's constantly reading characters (one at a
time), I would think that it would constantly reset its timeout timer.
But perhaps the timeout applies to the whole gdb_test command.  I don't
recall, I haven't touched that in a while.

Anyhow, a common way to fix this without bumping the timeout is to
change the test to use a line by line approach.  Typically by using
gdb_test_multiple to consume one line at a time and to keep reading
until the prompt is seen.  The test can set a flag to indicate whether
the searched-for string has been seen, and do a gdb_assert at the end.
There might be some smarter ways to do this today, I'm not super
up-to-date with the latest testsuite improvements.

Simon