[PATCH v4 10/11] Add maint set/show max-worker-threads

Tom Tromey
2019-10-01T20:12:43Z

This adds maint commands to control the maximum number of worker
threads that gdb can use.

gdb/ChangeLog
2019-10-01 Tom Tromey <tom@tromey.com>

* NEWS: Add entry.
* maint.c (_initialize_maint_cmds): Add "max-worker-threads" maint
commands.

gdb/doc/ChangeLog
2019-10-01 Tom Tromey <tom@tromey.com>

* gdb.texinfo (Maintenance Commands): Document new maint
commands.
---
gdb/ChangeLog | 6 ++++++
gdb/NEWS | 6 ++++++
gdb/doc/ChangeLog | 5 +++++
gdb/doc/gdb.texinfo | 14 ++++++++++++++
gdb/maint.c | 12 ++++++++++++
5 files changed, 43 insertions(+)

diff --git a/gdb/NEWS b/gdb/NEWS
index 779fd91d3a6..7d4988f6cb0 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -122,6 +122,12 @@ set style highlight background COLOR
set style highlight intensity VALUE
Control the styling of highlightings.

+maint set max-worker-threads
+maint show max-worker-threads
+ Control the maximum number of worker threads that can be used by GDB.
+ The default is "unlimited". Currently worker threads are only used when
+ demangling the names of linker symbols.
+
maint set test-settings KIND
maint show test-settings KIND
A set of commands used by the testsuite for exercising the settings
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index f2713c03960..04a40091de4 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -37663,6 +37663,20 @@ with the DWARF frame unwinders enabled.

If DWARF frame unwinders are not supported for a particular target
architecture, then enabling this flag does not cause them to be used.
+
+@kindex maint set max-worker-threads
+@kindex maint show max-worker-threads
+@item maint set max-worker-threads
+@item maint show max-worker-threads
+Control the number of worker threads that may be used by @value{GDBN}.
+On capable hosts, @value{GDBN} may use multiple threads to speed up
+certain CPU-intensive operations, such as demangling symbol names.
+While the number of threads used by @value{GDBN} may vary, this
+command can be used to set an upper bound on this number. The default
+is @code{unlimited}. Note that this only controls worker threads
+started by @value{GDBN} itself; libraries used by @value{GDBN} may
+start threads of their own.
+
@kindex maint set profile
@kindex maint show profile
@cindex profiling GDB
diff --git a/gdb/maint.c b/gdb/maint.c
index ec9f4abb264..8428bea4f92 100644
--- a/gdb/maint.c
+++ b/gdb/maint.c
@@ -40,6 +40,7 @@
#include "top.h"
#include "maint.h"
#include "gdbsupport/selftest.h"
+#include "gdbsupport/parallel-for.h"

#include "cli/cli-decode.h"
#include "cli/cli-utils.h"
@@ -1312,4 +1313,15 @@ When enabled GDB is profiled."),
show_maintenance_profile_p,
&maintenance_set_cmdlist,
&maintenance_show_cmdlist);
+
+ add_setshow_zuinteger_unlimited_cmd ("max-worker-threads",
+ class_maintenance,
+ &gdb::max_threads, _("\
+Set the maximum number of worker threads GDB can use."), _("\
+Set the maximum number of worker threads GDB can use."), _("\
+GDB may use multiple threads to speed up certain CPU-intensive operations,\n\
+such as demangling symbol names."),
+ NULL, NULL,
+ &maintenance_set_cmdlist,
+ &maintenance_show_cmdlist);
}
--
2.17.2