Non-stop inferior control.

* infrun.c (resume): In non-stop mode, always resume just one
	thread.
	(proceed): Don't call prepare_to_proceed in non-stop mode.
	(fetch_inferior_event): In non-stop mode, switch context before
	handling the event.
	(error_is_running, ensure_not_running): New.
	(handle_inferior_event): In non-stop mode: Mark only the event
	thread as stopped.  Require that the target module manages adding
	threads to the thread list.  Assert that there isn't a
	deferred_step_ptid set.  Don't switch to infwait_thread_hop_state.
	(normal_stop): Only mark not-running if inferior hasn't exited.
	In non-stop mode, only mark the event thread.

	* thread.c:Include "cli/cli-decode.h".
	(print_thread_info): Don't read from a running thread.
	Output "(running)" if thread is running.
	(switch_to_thread): Don't read stop_pc if thread is executing.
	(do_restore_current_thread_cleanup): Don't write to a running
	thread.
	(thread_apply_all_command): Don't read from a running thread.  In
	non-stop mode, do a full context-switch instead of just switching
	threads.
	(thread_apply_command): In non-stop mode, do a full context-switch
	instead of just switching threads.
	(do_captured_thread_select): Likewise.  Inform user if selected
	thread is running.
	(_initialize_thread): Mark "info threads" and "thread" and
	async_ok.

	* inf-loop.c (inferior_event_handler): In non-stop mode, don't
	unregister the target from the event loop.

	* infcmd.c (continue_command, step_1, jump_command)
	(signal_command): Ensure the selected thread isn't running.
	(interrupt_target_command): In non-stop mode, interrupt only the
	selected thread.

	* inferior.h (error_is_running, ensure_not_running): Declare.

	* target.h (struct target_ops): Add ptid argument to the to_stop
	member.
	(target_stop): Add ptid_t argument.

	* target.c (update_current_target): Add ptid argument to to_stop's
	type.
	(debug_to_stop): Add ptid_t argument.
	(debug_to_rcmd): Set to_stop_ptid.

	* remote.c (remote_stop): Add ptid_t argument.
	(async_remote_interrupt): Add inferior_ptid to target_stop.
	* inf-ptrace.c (inf_ptrace_stop): Add ptid argument.

	* Makefile.in (thread.o): Depend on $(cli_decode_h).
This commit is contained in:
Pedro Alves 2008-07-09 22:42:43 +00:00
parent 59f0d5d953
commit 94cc34afe2
11 changed files with 258 additions and 72 deletions

View File

@ -1,3 +1,61 @@
2008-07-09 Pedro Alves <pedro@codesourcery.com>
Non-stop inferior control.
* infrun.c (resume): In non-stop mode, always resume just one
thread.
(proceed): Don't call prepare_to_proceed in non-stop mode.
(fetch_inferior_event): In non-stop mode, switch context before
handling the event.
(error_is_running, ensure_not_running): New.
(handle_inferior_event): In non-stop mode: Mark only the event
thread as stopped. Require that the target module manages adding
threads to the thread list. Assert that there isn't a
deferred_step_ptid set. Don't switch to infwait_thread_hop_state.
(normal_stop): Only mark not-running if inferior hasn't exited.
In non-stop mode, only mark the event thread.
* thread.c:Include "cli/cli-decode.h".
(print_thread_info): Don't read from a running thread.
Output "(running)" if thread is running.
(switch_to_thread): Don't read stop_pc if thread is executing.
(do_restore_current_thread_cleanup): Don't write to a running
thread.
(thread_apply_all_command): Don't read from a running thread. In
non-stop mode, do a full context-switch instead of just switching
threads.
(thread_apply_command): In non-stop mode, do a full context-switch
instead of just switching threads.
(do_captured_thread_select): Likewise. Inform user if selected
thread is running.
(_initialize_thread): Mark "info threads" and "thread" and
async_ok.
* inf-loop.c (inferior_event_handler): In non-stop mode, don't
unregister the target from the event loop.
* infcmd.c (continue_command, step_1, jump_command)
(signal_command): Ensure the selected thread isn't running.
(interrupt_target_command): In non-stop mode, interrupt only the
selected thread.
* inferior.h (error_is_running, ensure_not_running): Declare.
* target.h (struct target_ops): Add ptid argument to the to_stop
member.
(target_stop): Add ptid_t argument.
* target.c (update_current_target): Add ptid argument to to_stop's
type.
(debug_to_stop): Add ptid_t argument.
(debug_to_rcmd): Set to_stop_ptid.
* remote.c (remote_stop): Add ptid_t argument.
(async_remote_interrupt): Add inferior_ptid to target_stop.
* inf-ptrace.c (inf_ptrace_stop): Add ptid argument.
* Makefile.in (thread.o): Depend on $(cli_decode_h).
2008-07-09 Pedro Alves <pedro@codesourcery.com>
Don't rely on ecs->wait_for_more.

View File

@ -2921,7 +2921,7 @@ target-memory.o: target-memory.c $(defs_h) $(vec_h) $(target_h) \
thread.o: thread.c $(defs_h) $(symtab_h) $(frame_h) $(inferior_h) \
$(environ_h) $(value_h) $(target_h) $(gdbthread_h) $(exceptions_h) \
$(command_h) $(gdbcmd_h) $(regcache_h) $(gdb_h) $(gdb_string_h) \
$(ui_out_h) $(observer_h) $(annotate_h)
$(ui_out_h) $(observer_h) $(annotate_h) $(cli_decode_h)
top.o: top.c $(defs_h) $(gdbcmd_h) $(call_cmds_h) $(cli_cmds_h) \
$(cli_script_h) $(cli_setshow_h) $(cli_decode_h) $(symtab_h) \
$(inferior_h) $(exceptions_h) $(target_h) $(breakpoint_h) \

View File

@ -73,11 +73,15 @@ inferior_event_handler (enum inferior_event_type event_type,
break;
case INF_EXEC_COMPLETE:
/* Unregister the inferior from the event loop. This is done so that
when the inferior is not running we don't get distracted by
spurious inferior output. */
if (target_has_execution)
target_async (NULL, 0);
if (!non_stop)
{
/* Unregister the inferior from the event loop. This is done
so that when the inferior is not running we don't get
distracted by spurious inferior output. */
if (target_has_execution)
target_async (NULL, 0);
}
/* The call to async_enable_stdin below resets 'sync_execution'.
However, if sync_execution is 1 now, we also need to show the

View File

@ -297,7 +297,7 @@ inf_ptrace_kill (void)
/* Stop the inferior. */
static void
inf_ptrace_stop (void)
inf_ptrace_stop (ptid_t ptid)
{
/* Send a SIGINT to the process group. This acts just like the user
typed a ^C on the controlling terminal. Note that using a

View File

@ -613,6 +613,7 @@ continue_command (char *proc_count_exp, int from_tty)
{
int async_exec = 0;
ERROR_NO_INFERIOR;
ensure_not_running ();
/* Find out whether we must run in the background. */
if (proc_count_exp != NULL)
@ -714,6 +715,7 @@ step_1 (int skip_subroutines, int single_inst, char *count_string)
int thread = -1;
ERROR_NO_INFERIOR;
ensure_not_running ();
if (count_string)
async_exec = strip_bg_char (&count_string);
@ -936,6 +938,7 @@ jump_command (char *arg, int from_tty)
int async_exec = 0;
ERROR_NO_INFERIOR;
ensure_not_running ();
/* Find out whether we must run in the background. */
if (arg != NULL)
@ -1036,6 +1039,7 @@ signal_command (char *signum_exp, int from_tty)
dont_repeat (); /* Too dangerous. */
ERROR_NO_INFERIOR;
ensure_not_running ();
/* Find out whether we must run in the background. */
if (signum_exp != NULL)
@ -2102,7 +2106,8 @@ interrupt_target_command (char *args, int from_tty)
if (target_can_async_p ())
{
dont_repeat (); /* Not for the faint of heart */
target_stop ();
target_stop (inferior_ptid);
}
}

View File

@ -245,6 +245,12 @@ extern void get_last_target_status(ptid_t *ptid,
extern void follow_inferior_reset_breakpoints (void);
/* Throw an error indicating the current thread is running. */
extern void error_is_running (void);
/* Calls error_is_running if the current thread is running. */
extern void ensure_not_running (void);
/* From infcmd.c */
extern void tty_command (char *, int);

View File

@ -1056,9 +1056,15 @@ a command like `return' or `jump' to continue execution."));
resume_ptid = inferior_ptid;
}
if ((scheduler_mode == schedlock_on)
|| (scheduler_mode == schedlock_step
&& (step || singlestep_breakpoints_inserted_p)))
if (non_stop)
{
/* With non-stop mode on, threads are always handled
individually. */
resume_ptid = inferior_ptid;
}
else if ((scheduler_mode == schedlock_on)
|| (scheduler_mode == schedlock_step
&& (step || singlestep_breakpoints_inserted_p)))
{
/* User-settable 'scheduler' mode requires solo thread resume. */
resume_ptid = inferior_ptid;
@ -1219,19 +1225,27 @@ proceed (CORE_ADDR addr, enum target_signal siggnal, int step)
"infrun: proceed (addr=0x%s, signal=%d, step=%d)\n",
paddr_nz (addr), siggnal, step);
/* In a multi-threaded task we may select another thread
and then continue or step.
if (non_stop)
/* In non-stop, each thread is handled individually. The context
must already be set to the right thread here. */
;
else
{
/* In a multi-threaded task we may select another thread and
then continue or step.
But if the old thread was stopped at a breakpoint, it
will immediately cause another breakpoint stop without
any execution (i.e. it will report a breakpoint hit
incorrectly). So we must step over it first.
But if the old thread was stopped at a breakpoint, it will
immediately cause another breakpoint stop without any
execution (i.e. it will report a breakpoint hit incorrectly).
So we must step over it first.
prepare_to_proceed checks the current thread against the thread
that reported the most recent event. If a step-over is required
it returns TRUE and sets the current thread to the old thread. */
if (prepare_to_proceed (step))
oneproc = 1;
prepare_to_proceed checks the current thread against the
thread that reported the most recent event. If a step-over
is required it returns TRUE and sets the current thread to
the old thread. */
if (prepare_to_proceed (step))
oneproc = 1;
}
if (oneproc)
{
@ -1535,6 +1549,15 @@ fetch_inferior_event (void *client_data)
else
ecs->ptid = target_wait (waiton_ptid, &ecs->ws);
if (non_stop
&& ecs->ws.kind != TARGET_WAITKIND_IGNORE
&& ecs->ws.kind != TARGET_WAITKIND_EXITED
&& ecs->ws.kind != TARGET_WAITKIND_SIGNALLED)
/* In non-stop mode, each thread is handled individually. Switch
early, so the global state is set correctly for this
thread. */
context_switch (ecs->ptid);
/* Now figure out what to do with the result of the result. */
handle_inferior_event (ecs);
@ -1745,6 +1768,20 @@ init_infwait_state (void)
infwait_state = infwait_normal_state;
}
void
error_is_running (void)
{
error (_("\
Cannot execute this command while the selected thread is running."));
}
void
ensure_not_running (void)
{
if (is_running (inferior_ptid))
error_is_running ();
}
/* Given an execution control state that has been freshly filled in
by an event from the inferior, figure out what it means and take
appropriate action. */
@ -1818,10 +1855,16 @@ handle_inferior_event (struct execution_control_state *ecs)
&& ecs->ws.kind != TARGET_WAITKIND_SIGNALLED && ecs->new_thread_event)
add_thread (ecs->ptid);
/* Mark all threads as not-executing. In non-stop, this should be
adjusted to only mark ecs->ptid. */
if (ecs->ws.kind != TARGET_WAITKIND_IGNORE)
set_executing (pid_to_ptid (-1), 0);
{
/* Mark the non-executing threads accordingly. */
if (!non_stop
|| ecs->ws.kind == TARGET_WAITKIND_EXITED
|| ecs->ws.kind == TARGET_WAITKIND_SIGNALLED)
set_executing (pid_to_ptid (-1), 0);
else
set_executing (ecs->ptid, 0);
}
switch (ecs->ws.kind)
{
@ -2059,15 +2102,22 @@ handle_inferior_event (struct execution_control_state *ecs)
return;
}
/* We may want to consider not doing a resume here in order to give
the user a chance to play with the new thread. It might be good
to make that a user-settable option. */
/* At this point, all threads are stopped (happens automatically in
either the OS or the native code). Therefore we need to continue
all threads in order to make progress. */
if (ecs->new_thread_event)
{
if (non_stop)
/* Non-stop assumes that the target handles adding new threads
to the thread list. */
internal_error (__FILE__, __LINE__, "\
targets should add new threads to the thread list themselves in non-stop mode.");
/* We may want to consider not doing a resume here in order to
give the user a chance to play with the new thread. It might
be good to make that a user-settable option. */
/* At this point, all threads are stopped (happens automatically
in either the OS or the native code). Therefore we need to
continue all threads in order to make progress. */
target_resume (RESUME_ALL, 0, TARGET_SIGNAL_0);
prepare_to_wait (ecs);
return;
@ -2134,6 +2184,9 @@ handle_inferior_event (struct execution_control_state *ecs)
if (!ptid_equal (deferred_step_ptid, null_ptid))
{
/* In non-stop mode, there's never a deferred_step_ptid set. */
gdb_assert (!non_stop);
/* If we stopped for some other reason than single-stepping, ignore
the fact that we were supposed to switch back. */
if (stop_signal == TARGET_SIGNAL_TRAP)
@ -2282,8 +2335,13 @@ handle_inferior_event (struct execution_control_state *ecs)
if (!ptid_equal (inferior_ptid, ecs->ptid))
context_switch (ecs->ptid);
waiton_ptid = ecs->ptid;
infwait_state = infwait_thread_hop_state;
if (!non_stop)
{
/* Only need to require the next event from this
thread in all-stop mode. */
waiton_ptid = ecs->ptid;
infwait_state = infwait_thread_hop_state;
}
tss->stepping_over_breakpoint = 1;
keep_going (ecs);
@ -3838,7 +3896,16 @@ done:
/* Delete the breakpoint we stopped at, if it wants to be deleted.
Delete any breakpoint that is to be deleted at the next stop. */
breakpoint_auto_delete (stop_bpstat);
set_running (pid_to_ptid (-1), 0);
if (target_has_execution
&& last.kind != TARGET_WAITKIND_SIGNALLED
&& last.kind != TARGET_WAITKIND_EXITED)
{
if (!non_stop)
set_running (pid_to_ptid (-1), 0);
else
set_running (inferior_ptid, 0);
}
}
static int

View File

@ -155,7 +155,7 @@ static void init_remote_ops (void);
static void init_extended_remote_ops (void);
static void remote_stop (void);
static void remote_stop (ptid_t);
static int ishex (int ch, int *val);
@ -3269,7 +3269,7 @@ async_remote_interrupt (gdb_client_data arg)
if (remote_debug)
fprintf_unfiltered (gdb_stdlog, "remote_interrupt called\n");
target_stop ();
target_stop (inferior_ptid);
}
/* Perform interrupt, if the first attempt did not succeed. Just give
@ -3323,7 +3323,7 @@ remote_interrupt_twice (int signo)
interrupt is requested, either by the command line or the GUI, we
will eventually end up here. */
static void
remote_stop (void)
remote_stop (ptid_t ptid)
{
/* Send a break or a ^C, depending on user preference. */
if (remote_debug)

View File

@ -165,7 +165,7 @@ static void debug_to_notice_signals (ptid_t);
static int debug_to_thread_alive (ptid_t);
static void debug_to_stop (void);
static void debug_to_stop (ptid_t);
/* NOTE: cagney/2004-09-29: Many targets reference this variable in
wierd and mysterious ways. Putting the variable here lets those
@ -630,7 +630,7 @@ update_current_target (void)
(char *(*) (struct thread_info *))
return_zero);
de_fault (to_stop,
(void (*) (void))
(void (*) (ptid_t))
target_ignore);
current_target.to_xfer_partial = current_xfer_partial;
de_fault (to_rcmd,
@ -2997,11 +2997,12 @@ debug_to_find_new_threads (void)
}
static void
debug_to_stop (void)
debug_to_stop (ptid_t ptid)
{
debug_target.to_stop ();
debug_target.to_stop (ptid);
fprintf_unfiltered (gdb_stdlog, "target_stop ()\n");
fprintf_unfiltered (gdb_stdlog, "target_stop (%s)\n",
target_pid_to_str (ptid));
}
static void

View File

@ -401,7 +401,7 @@ struct target_ops
void (*to_find_new_threads) (void);
char *(*to_pid_to_str) (ptid_t);
char *(*to_extra_thread_info) (struct thread_info *);
void (*to_stop) (void);
void (*to_stop) (ptid_t);
void (*to_rcmd) (char *command, struct ui_file *output);
char *(*to_pid_to_exec_file) (int pid);
void (*to_log_command) (const char *);
@ -906,7 +906,7 @@ int target_follow_fork (int follow_child);
Unix, this should act like SIGSTOP). This function is normally
used by GUIs to implement a stop button. */
#define target_stop current_target.to_stop
#define target_stop(ptid) (*current_target.to_stop) (ptid)
/* Send the specified COMMAND to the target's monitor
(shell,interpreter) for execution. The result of the query is

View File

@ -42,6 +42,8 @@
#include "observer.h"
#include "annotate.h"
#include "cli/cli-decode.h"
/* Definition of struct thread_info exported to gdbthread.h */
/* Prototypes for exported functions. */
@ -640,9 +642,12 @@ print_thread_info (struct ui_out *uiout, int requested_thread)
int current_thread = -1;
/* Backup current thread and selected frame. */
saved_frame_id = get_frame_id (get_selected_frame (NULL));
old_chain = make_cleanup_restore_current_thread (inferior_ptid, saved_frame_id);
if (!is_running (inferior_ptid))
saved_frame_id = get_frame_id (get_selected_frame (NULL));
else
saved_frame_id = null_frame_id;
old_chain = make_cleanup_restore_current_thread (inferior_ptid, saved_frame_id);
make_cleanup_ui_out_list_begin_end (uiout, "threads");
prune_threads ();
@ -677,12 +682,18 @@ print_thread_info (struct ui_out *uiout, int requested_thread)
ui_out_text (uiout, ")");
}
ui_out_text (uiout, " ");
/* That switch put us at the top of the stack (leaf frame). */
switch_to_thread (tp->ptid);
print_stack_frame (get_selected_frame (NULL),
/* For MI output, print frame level. */
ui_out_is_mi_like_p (uiout),
LOCATION);
if (tp->running_)
ui_out_text (uiout, "(running)\n");
else
{
/* The switch below puts us at the top of the stack (leaf
frame). */
switch_to_thread (tp->ptid);
print_stack_frame (get_selected_frame (NULL),
/* For MI output, print frame level. */
ui_out_is_mi_like_p (uiout),
LOCATION);
}
do_cleanups (chain2);
}
@ -698,6 +709,9 @@ print_thread_info (struct ui_out *uiout, int requested_thread)
ui_out_field_int (uiout, "current-thread-id", current_thread);
}
if (is_running (inferior_ptid))
return;
/* If case we were not able to find the original frame, print the
new selected frame. */
if (frame_find_by_id (saved_frame_id) == NULL)
@ -736,7 +750,11 @@ switch_to_thread (ptid_t ptid)
inferior_ptid = ptid;
reinit_frame_cache ();
registers_changed ();
stop_pc = read_pc ();
if (!is_executing (ptid))
stop_pc = read_pc ();
else
stop_pc = ~(CORE_ADDR) 0;
}
static void
@ -773,7 +791,12 @@ do_restore_current_thread_cleanup (void *arg)
{
struct current_thread_cleanup *old = arg;
restore_current_thread (old->inferior_ptid);
restore_selected_frame (old->selected_frame_id);
/* A command like 'thread apply all $exec_command&' may change the
running state of the originally selected thread, so we have to
recheck it here. */
if (!is_running (old->inferior_ptid))
restore_selected_frame (old->selected_frame_id);
xfree (old);
}
@ -801,8 +824,7 @@ static void
thread_apply_all_command (char *cmd, int from_tty)
{
struct thread_info *tp;
struct cleanup *old_chain;
struct cleanup *saved_cmd_cleanup_chain;
struct cleanup *old_chain = make_cleanup (null_cleanup, 0);
char *saved_cmd;
struct frame_id saved_frame_id;
ptid_t current_ptid;
@ -812,8 +834,12 @@ thread_apply_all_command (char *cmd, int from_tty)
error (_("Please specify a command following the thread ID list"));
current_ptid = inferior_ptid;
saved_frame_id = get_frame_id (get_selected_frame (NULL));
old_chain = make_cleanup_restore_current_thread (inferior_ptid, saved_frame_id);
if (!is_running (inferior_ptid))
saved_frame_id = get_frame_id (get_selected_frame (NULL));
else
saved_frame_id = null_frame_id;
make_cleanup_restore_current_thread (inferior_ptid, saved_frame_id);
/* It is safe to update the thread list now, before
traversing it for "thread apply all". MVS */
@ -822,11 +848,15 @@ thread_apply_all_command (char *cmd, int from_tty)
/* Save a copy of the command in case it is clobbered by
execute_command */
saved_cmd = xstrdup (cmd);
saved_cmd_cleanup_chain = make_cleanup (xfree, (void *) saved_cmd);
make_cleanup (xfree, saved_cmd);
for (tp = thread_list; tp; tp = tp->next)
if (thread_alive (tp))
{
switch_to_thread (tp->ptid);
if (non_stop)
context_switch_to (tp->ptid);
else
switch_to_thread (tp->ptid);
printf_filtered (_("\nThread %d (%s):\n"),
tp->num, target_tid_to_str (inferior_ptid));
execute_command (cmd, from_tty);
@ -836,12 +866,10 @@ thread_apply_all_command (char *cmd, int from_tty)
if (!ptid_equal (current_ptid, inferior_ptid))
thread_has_changed = 1;
do_cleanups (saved_cmd_cleanup_chain);
do_cleanups (old_chain);
/* Print stack frame only if we changed thread. */
if (thread_has_changed)
if (thread_has_changed && !is_running (inferior_ptid))
print_stack_frame (get_current_frame (), 1, SRC_LINE);
}
static void
@ -865,7 +893,11 @@ thread_apply_command (char *tidlist, int from_tty)
error (_("Please specify a command following the thread ID list"));
current_ptid = inferior_ptid;
saved_frame_id = get_frame_id (get_selected_frame (NULL));
if (!is_running (inferior_ptid))
saved_frame_id = get_frame_id (get_selected_frame (NULL));
else
saved_frame_id = null_frame_id;
old_chain = make_cleanup_restore_current_thread (inferior_ptid, saved_frame_id);
/* Save a copy of the command in case it is clobbered by
@ -909,7 +941,10 @@ thread_apply_command (char *tidlist, int from_tty)
warning (_("Thread %d has terminated."), start);
else
{
switch_to_thread (tp->ptid);
if (non_stop)
context_switch_to (tp->ptid);
else
switch_to_thread (tp->ptid);
printf_filtered (_("\nThread %d (%s):\n"), tp->num,
target_tid_to_str (inferior_ptid));
execute_command (cmd, from_tty);
@ -977,7 +1012,10 @@ do_captured_thread_select (struct ui_out *uiout, void *tidstr)
if (!thread_alive (tp))
error (_("Thread ID %d has terminated."), num);
switch_to_thread (tp->ptid);
if (non_stop)
context_switch_to (tp->ptid);
else
switch_to_thread (tp->ptid);
ui_out_text (uiout, "[Switching to thread ");
ui_out_field_int (uiout, "new-thread-id", pid_to_thread_id (inferior_ptid));
@ -985,7 +1023,11 @@ do_captured_thread_select (struct ui_out *uiout, void *tidstr)
ui_out_text (uiout, target_tid_to_str (inferior_ptid));
ui_out_text (uiout, ")]");
print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC);
if (!tp->running_)
print_stack_frame (get_selected_frame (NULL), 1, SRC_AND_LOC);
else
ui_out_text (uiout, "(running)\n");
return GDB_RC_OK;
}
@ -1005,14 +1047,17 @@ void
_initialize_thread (void)
{
static struct cmd_list_element *thread_apply_list = NULL;
struct cmd_list_element *c;
add_info ("threads", info_threads_command,
_("IDs of currently known threads."));
c = add_info ("threads", info_threads_command,
_("IDs of currently known threads."));
set_cmd_async_ok (c);
add_prefix_cmd ("thread", class_run, thread_command, _("\
c = add_prefix_cmd ("thread", class_run, thread_command, _("\
Use this command to switch between threads.\n\
The new thread ID must be currently known."),
&thread_cmd_list, "thread ", 1, &cmdlist);
&thread_cmd_list, "thread ", 1, &cmdlist);
set_cmd_async_ok (c);
add_prefix_cmd ("apply", class_run, thread_apply_command,
_("Apply a command to a list of threads."),