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Consider a case where many threads (thousands) keep hitting a breakpoint whose condition evaluates to false. random_pending_event_thread is responsible for selecting a thread from an inferior among all that are resumed with a pending wait status. It is currently implemented by walking the inferior's thread list twice: once to count the number of candidates and once to select a random one. Since we now maintain a per target list of resumed threads with pending event, we can implement this more efficiently by walking that list and selecting the first thread that matches the criteria (random_pending_event_thread looks for an thread from a specific inferior, and possibly a filter ptid). It will be faster especially in the common case where there isn't any resumed thread with pending event. Currently, we have to iterate the thread list to figure this out. With this patch, the list of resumed threads with pending event will be empty, so it's quick to figure out. The random selection is kept, but is moved to process_stratum_target::random_resumed_with_pending_wait_status. The same technique is used: do a first pass to count the number of candidates, and do a second pass to select a random one. But given that the list of resumed threads with pending wait statuses will generally be short, or at least shorter than the full thread list, it should be quicker. Note that this isn't completely true, in case there are multiple inferiors on the same target. Imagine that inferior A has 10k resumed threads with pending wait statuses, and random_pending_event_thread is called with inferior B. We'll need to go through the list that contains inferior A's threads to realize that inferior B has no resumed threads with pending wait status. But I think that this is a corner / pathological case. And a possible fix for this situation would be to make random_pending_event_thread work per-process-target, rather than per-inferior. Change-Id: I1b71d01beaa500a148b5b9797745103e13917325
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.