From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by sourceware.org (Postfix) with ESMTPS id 66AC83858C2C for ; Tue, 24 Aug 2021 11:10:43 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 66AC83858C2C Received: from imap1.suse-dmz.suse.de (imap1.suse-dmz.suse.de [192.168.254.73]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 824AE21E1C; Tue, 24 Aug 2021 11:10:42 +0000 (UTC) Received: from imap1.suse-dmz.suse.de (imap1.suse-dmz.suse.de [192.168.254.73]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap1.suse-dmz.suse.de (Postfix) with ESMTPS id 67855137F3; Tue, 24 Aug 2021 11:10:42 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap1.suse-dmz.suse.de with ESMTPSA id xscfGLLTJGFdFwAAGKfGzw (envelope-from ); Tue, 24 Aug 2021 11:10:42 +0000 Subject: [PING][RFC][gdb/doc] Document non-stop attach behaviour From: Tom de Vries To: gdb-patches@sourceware.org Cc: Pedro Alves , Simon Marchi References: <20210607132127.GA10588@delia.home> Message-ID: Date: Tue, 24 Aug 2021 13:10:42 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <20210607132127.GA10588@delia.home> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-12.1 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 24 Aug 2021 11:10:53 -0000 On 6/7/21 3:21 PM, Tom de Vries wrote: > Hi, > > While investigating PR27908, I got confused about what the proper behaviour > is when attaching to a multi-threaded program in non-stop mode. > > In particular, when running a script that issues an "info threads" after an > attach in non-stop mode, it can show a non-current thread as still running: > ... > $ ./a.out & pid=$!; \ > gdb -q \ > -iex "set trace-commands on" \ > -iex "set pagination off" \ > -iex "set non-stop on" \ > -p $pid \ > -ex "info threads" > [2] 10038 > +set pagination off > +set non-stop on > Attaching to process 10038 > [New LWP 10040] > main () at test.c:37 > 37 while (1) > +info threads > Id Target Id Frame > * 1 Thread 0x7f63547a8740 (LWP 10038) "a.out" main () at t.c:37 > 2 Thread 0x7f6353fd7700 (LWP 10040) "a.out" (running) > (gdb) > Thread 2 "a.out" stopped. > thread_func (p=0x0) at test.c:13 > 13 while (1) > ... > > An "info threads" after the 'Thread 2 "a.out" stopped' message will show it as > stopped though: > ... > info threads > +info threads > Id Target Id Frame > * 1 Thread 0x7f63547a8740 (LWP 10038) "a.out" main () at t.c:37 > 2 Thread 0x7f6353fd7700 (LWP 10040) "a.out" thread_func (p=0x0) at t.c:13 > (gdb) > ... > > In conclusion, it seems that attaching in non-stop mode stops all threads, > just like in all-stop mode. But the stopping of non-current threads is > visible to the user. > > Update the non-stop documentation to describe the attach behaviour in some > detail. > > Any comments? > Ping. Thanks, - Tom > [gdb/doc] Document non-stop attach behaviour > > gdb/doc/ChangeLog: > > 2021-06-07 Tom de Vries > > * gdb.texinfo (Non-Stop Mode): Describe non-stop attach behaviour. > > --- > gdb/doc/gdb.texinfo | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo > index d09b86cda95..0fd7ab16150 100644 > --- a/gdb/doc/gdb.texinfo > +++ b/gdb/doc/gdb.texinfo > @@ -6957,6 +6957,13 @@ one thread while allowing others to run freely, stepping > one thread while holding all others stopped, or stepping several threads > independently and simultaneously. > > +Note that attaching in non-stop mode stops all threads, just as in > +all-stop mode. However, while in all-stop mode the attach command is > +finished only once all threads are stopped, in non-stop mode it's > +finished once the current thread is stopped. Consequently, it's > +briefly possible to observe non-current threads still running after an > +attach. > + > To enter non-stop mode, use this sequence of commands before you run > or attach to your program: > >