@itemize @bullet
@item automatic notification of new threads
-@item @samp{thread @var{threadno}}, a command to switch among threads
+@item @samp{thread @var{thread-id}}, a command to switch among threads
@item @samp{info threads}, a command to inquire about existing threads
-@item @samp{thread apply [@var{threadno}] [@var{all}] @var{args}},
+@item @samp{thread apply [@var{thread-id-list}] [@var{all}] @var{args}},
a command to apply a command to a list of threads
@item thread-specific breakpoints
@item @samp{set print thread-events}, which controls printing of
@c multithread systems permit starting a program with multiple
@c threads ab initio?
-@cindex thread number
+@anchor{thread numbers}
+@cindex thread number, per inferior
@cindex thread identifier (GDB)
-For debugging purposes, @value{GDBN} associates its own thread
-number---always a single integer---with each thread in your program.
+For debugging purposes, @value{GDBN} associates its own thread number
+---always a single integer---with each thread of an inferior. This
+number is unique between all threads of an inferior, but not unique
+between threads of different inferiors.
+
+@cindex qualified thread ID
+You can refer to a given thread in an inferior using the qualified
+@var{inferior-num}.@var{thread-num} syntax, also known as
+@dfn{qualified thread ID}, with @var{inferior-num} being the inferior
+number and @var{thread-num} being the thread number of the given
+inferior. For example, thread @code{2.3} refers to thread number 3 of
+inferior 2. If you omit @var{inferior-num} (e.g., @code{thread 3}),
+then @value{GDBN} infers you're referring to a thread of the current
+inferior.
+
+Until you create a second inferior, @value{GDBN} does not show the
+@var{inferior-num} part of thread IDs, even though you can always use
+the full @var{inferior-num}.@var{thread-num} form to refer to threads
+of inferior 1, the initial inferior.
+
+@anchor{thread ID lists}
+@cindex thread ID lists
+Some commands accept a space-separated @dfn{thread ID list} as
+argument. A list element can be a thread ID as shown in the first
+field of the @samp{info threads} display, with or without an inferior
+qualifier (e.g., @samp{2.1} or @samp{1}); or can be a range of thread
+numbers, again with or without an inferior qualifier, as in
+@var{inf1}.@var{thr1}-@var{thr2} or @var{thr1}-@var{thr2} (e.g.,
+@samp{1.2-4} or @samp{2-4}). For example, if the current inferior is
+1, the thread list @samp{1 2-3 4.5 6.7-9} includes threads 1 to 3 of
+inferior 1, thread 5 of inferior 4 and threads 7 to 9 of inferior 6.
+That is, in expanded qualified form, the same as @samp{1.1 1.2 1.3 4.5
+6.7 6.8 6.9}.
+
+@anchor{global thread numbers}
+@cindex global thread number
+@cindex global thread identifier (GDB)
+In addition to a @emph{per-inferior} number, each thread is also
+assigned a unique @emph{global} number, also known as @dfn{global
+thread ID}, a single integer. Unlike the thread number component of
+the thread ID, no two threads have the same global ID, even when
+you're debugging multiple inferiors.
From @value{GDBN}'s perspective, a process always has at least one
thread. In other words, @value{GDBN} assigns a thread number to the
program's ``main thread'' even if the program is not multi-threaded.
+@vindex $_thread@r{, convenience variable}
+The debugger convenience variable @samp{$_thread} contains the
+per-inferior thread number of the current thread. You may find this
+useful in writing breakpoint conditional expressions, command scripts,
+and so forth. @xref{Convenience Vars,, Convenience Variables}, for
+general information on convenience variables.
+
@table @code
@kindex info threads
-@item info threads @r{[}@var{id}@dots{}@r{]}
-Display a summary of all threads currently in your program. Optional
-argument @var{id}@dots{} is one or more thread ids separated by spaces, and
-means to print information only about the specified thread or threads.
+@item info threads @r{[}@var{thread-id-list}@r{]}
+
+Display information about one or more threads. With no arguments
+displays information about all threads. You can specify the list of
+threads that you want to display using the thread ID list syntax
+(@pxref{thread ID lists}).
+
@value{GDBN} displays for each thread (in this order):
@enumerate
@item
-the thread number assigned by @value{GDBN}
+the per-inferior thread number assigned by @value{GDBN}
@item
the target system's thread identifier (@var{systag})
at threadtest.c:68
@end smallexample
+If you're debugging multiple inferiors, @value{GDBN} displays thread
+IDs using the qualified @var{inferior-num}.@var{thread-num} format.
+Otherwise, only @var{thread-num} is shown:
+
+@smallexample
+(@value{GDBP}) info threads
+ Id Target Id Frame
+ 1.1 process 35 thread 13 main (argc=1, argv=0x7ffffff8)
+ 1.2 process 35 thread 23 0x34e5 in sigpause ()
+ 1.3 process 35 thread 27 0x34e5 in sigpause ()
+* 2.1 process 65 thread 1 main (argc=1, argv=0x7ffffff8)
+@end smallexample
+
On Solaris, you can display more information about user threads with a
Solaris-specific command:
@end table
@table @code
-@kindex thread @var{threadno}
-@item thread @var{threadno}
-Make thread number @var{threadno} the current thread. The command
-argument @var{threadno} is the internal @value{GDBN} thread number, as
-shown in the first field of the @samp{info threads} display.
-@value{GDBN} responds by displaying the system identifier of the thread
-you selected, and its current stack frame summary:
+@kindex thread @var{thread-id}
+@item thread @var{thread-id}
+Make thread ID @var{thread-id} the current thread. The command
+argument @var{thread-id} is the @value{GDBN} thread ID, as shown in
+the first field of the @samp{info threads} display, with or without an
+inferior qualifier (e.g., @samp{2.1} or @samp{1}).
+
+@value{GDBN} responds by displaying the system identifier of the
+thread you selected, and its current stack frame summary:
@smallexample
(@value{GDBP}) thread 2
@samp{Switching to} depends on your system's conventions for identifying
threads.
-@vindex $_thread@r{, convenience variable}
-The debugger convenience variable @samp{$_thread} contains the number
-of the current thread. You may find this useful in writing breakpoint
-conditional expressions, command scripts, and so forth. See
-@xref{Convenience Vars,, Convenience Variables}, for general
-information on convenience variables.
-
@kindex thread apply
@cindex apply command to several threads
-@item thread apply [@var{threadno} | all [-ascending]] @var{command}
+@item thread apply [@var{thread-id-list} | all [-ascending]] @var{command}
The @code{thread apply} command allows you to apply the named
-@var{command} to one or more threads. Specify the numbers of the
-threads that you want affected with the command argument
-@var{threadno}. It can be a single thread number, one of the numbers
-shown in the first field of the @samp{info threads} display; or it
-could be a range of thread numbers, as in @code{2-4}. To apply
-a command to all threads in descending order, type @kbd{thread apply all
+@var{command} to one or more threads. Specify the threads that you
+want affected using the thread ID list syntax (@pxref{thread ID
+lists}), or specify @code{all} to apply to all threads. To apply a
+command to all threads in descending order, type @kbd{thread apply all
@var{command}}. To apply a command to all threads in ascending order,
type @kbd{thread apply all -ascending @var{command}}.
@table @code
@kindex watch
-@item watch @r{[}-l@r{|}-location@r{]} @var{expr} @r{[}thread @var{threadnum}@r{]} @r{[}mask @var{maskvalue}@r{]}
+@item watch @r{[}-l@r{|}-location@r{]} @var{expr} @r{[}thread @var{thread-id}@r{]} @r{[}mask @var{maskvalue}@r{]}
Set a watchpoint for an expression. @value{GDBN} will break when the
expression @var{expr} is written into by the program and its value
changes. The simplest (and the most popular) use of this command is
(@value{GDBP}) watch foo
@end smallexample
-If the command includes a @code{@r{[}thread @var{threadnum}@r{]}}
+If the command includes a @code{@r{[}thread @var{thread-id}@r{]}}
argument, @value{GDBN} breaks only when the thread identified by
-@var{threadnum} changes the value of @var{expr}. If any other threads
+@var{thread-id} changes the value of @var{expr}. If any other threads
change the value of @var{expr}, @value{GDBN} will not break. Note
that watchpoints restricted to a single thread in this way only work
with Hardware Watchpoints.
@end smallexample
@kindex rwatch
-@item rwatch @r{[}-l@r{|}-location@r{]} @var{expr} @r{[}thread @var{threadnum}@r{]} @r{[}mask @var{maskvalue}@r{]}
+@item rwatch @r{[}-l@r{|}-location@r{]} @var{expr} @r{[}thread @var{thread-id}@r{]} @r{[}mask @var{maskvalue}@r{]}
Set a watchpoint that will break when the value of @var{expr} is read
by the program.
@kindex awatch
-@item awatch @r{[}-l@r{|}-location@r{]} @var{expr} @r{[}thread @var{threadnum}@r{]} @r{[}mask @var{maskvalue}@r{]}
+@item awatch @r{[}-l@r{|}-location@r{]} @var{expr} @r{[}thread @var{thread-id}@r{]} @r{[}mask @var{maskvalue}@r{]}
Set a watchpoint that will break when @var{expr} is either read from
or written into by the program.
@table @code
@cindex breakpoints and threads
@cindex thread breakpoints
-@kindex break @dots{} thread @var{threadno}
-@item break @var{location} thread @var{threadno}
-@itemx break @var{location} thread @var{threadno} if @dots{}
+@kindex break @dots{} thread @var{thread-id}
+@item break @var{location} thread @var{thread-id}
+@itemx break @var{location} thread @var{thread-id} if @dots{}
@var{location} specifies source lines; there are several ways of
writing them (@pxref{Specify Location}), but the effect is always to
specify some source line.
-Use the qualifier @samp{thread @var{threadno}} with a breakpoint command
+Use the qualifier @samp{thread @var{thread-id}} with a breakpoint command
to specify that you only want @value{GDBN} to stop the program when a
-particular thread reaches this breakpoint. The @var{threadno} specifier
-is one of the numeric thread identifiers assigned by @value{GDBN}, shown
+particular thread reaches this breakpoint. The @var{thread-id} specifier
+is one of the thread identifiers assigned by @value{GDBN}, shown
in the first column of the @samp{info threads} display.
-If you do not specify @samp{thread @var{threadno}} when you set a
+If you do not specify @samp{thread @var{thread-id}} when you set a
breakpoint, the breakpoint applies to @emph{all} threads of your
program.
You can use the @code{thread} qualifier on conditional breakpoints as
-well; in this case, place @samp{thread @var{threadno}} before or
+well; in this case, place @samp{thread @var{thread-id}} before or
after the breakpoint condition, like this:
@smallexample
The number of the current inferior. @xref{Inferiors and
Programs, ,Debugging Multiple Inferiors and Programs}.
+@item $_thread
+The thread number of the current thread. @xref{thread numbers}.
+
@end table
@node Convenience Funs
@item task @var{taskno}
@cindex Ada task switching
-This command is like the @code{thread @var{threadno}}
+This command is like the @code{thread @var{thread-id}}
command (@pxref{Threads}). It switches the context of debugging
from the current task to the given task.
frontend may be operating on a wrong one. Therefore, each MI command
should explicitly specify which thread and frame to operate on. To
make it possible, each MI command accepts the @samp{--thread} and
-@samp{--frame} options, the value to each is @value{GDBN} identifier
-for thread and frame to operate on.
+@samp{--frame} options, the value to each is @value{GDBN} global
+identifier for thread and frame to operate on.
Usually, each top-level window in a frontend allows the user to select
a thread and a frame, and remembers the user selection for further
@table @code
@item *running,thread-id="@var{thread}"
-The target is now running. The @var{thread} field tells which
-specific thread is now running, and can be @samp{all} if all threads
-are running. The frontend should assume that no interaction with a
-running thread is possible after this notification is produced.
-The frontend should not assume that this notification is output
-only once for any command. @value{GDBN} may emit this notification
-several times, either for different threads, because it cannot resume
-all threads together, or even for a single thread, if the thread must
-be stepped though some code before letting it run freely.
+The target is now running. The @var{thread} field can be the global
+thread ID of the the thread that is now running, and it can be
+@samp{all} if all threads are running. The frontend should assume
+that no interaction with a running thread is possible after this
+notification is produced. The frontend should not assume that this
+notification is output only once for any command. @value{GDBN} may
+emit this notification several times, either for different threads,
+because it cannot resume all threads together, or even for a single
+thread, if the thread must be stepped though some code before letting
+it run freely.
@item *stopped,reason="@var{reason}",thread-id="@var{id}",stopped-threads="@var{stopped}",core="@var{core}"
The target has stopped. The @var{reason} field can have one of the
(@pxref{Set Catchpoints}) has been used.
@end table
-The @var{id} field identifies the thread that directly caused the stop
--- for example by hitting a breakpoint. Depending on whether all-stop
+The @var{id} field identifies the global thread ID of the thread
+that directly caused the stop -- for example by hitting a breakpoint.
+Depending on whether all-stop
mode is in effect (@pxref{All-Stop Mode}), @value{GDBN} may either
stop all threads, or only the thread that directly triggered the stop.
If all threads are stopped, the @var{stopped} field will have the
@item =thread-created,id="@var{id}",group-id="@var{gid}"
@itemx =thread-exited,id="@var{id}",group-id="@var{gid}"
A thread either was created, or has exited. The @var{id} field
-contains the @value{GDBN} identifier of the thread. The @var{gid}
+contains the global @value{GDBN} identifier of the thread. The @var{gid}
field identifies the thread group this thread belongs to.
@item =thread-selected,id="@var{id}"
@table @code
@item id
-The numeric id assigned to the thread by @value{GDBN}. This field is
+The global numeric id assigned to the thread by @value{GDBN}. This field is
always present.
@item target-id
@item -i @var{ignore-count}
Initialize the @var{ignore-count}.
@item -p @var{thread-id}
-Restrict the breakpoint to the specified @var{thread-id}.
+Restrict the breakpoint to the thread with the specified global
+@var{thread-id}.
@end table
@subsubheading Result
Set the ignore count of the breakpoint (@pxref{Conditions, ignore count})
to @var{ignore-count}.
@item -p @var{thread-id}
-Restrict the breakpoint to the specified @var{thread-id}.
+Restrict the breakpoint to the thread with the specified global
+@var{thread-id}.
@end table
@subsubheading Result
-thread-info [ @var{thread-id} ]
@end smallexample
-Reports information about either a specific thread, if
-the @var{thread-id} parameter is present, or about all
-threads. When printing information about all threads,
-also reports the current thread.
+Reports information about either a specific thread, if the
+@var{thread-id} parameter is present, or about all threads.
+@var{thread-id} is the thread's global thread ID. When printing
+information about all threads, also reports the global ID of the
+current thread.
@subsubheading @value{GDBN} Command
This field exists only for the current thread. It has the value @samp{*}.
@item id
-The identifier that @value{GDBN} uses to refer to the thread.
+The global identifier that @value{GDBN} uses to refer to the thread.
@item target-id
The identifier that the target uses to refer to the thread.
-thread-list-ids
@end smallexample
-Produces a list of the currently known @value{GDBN} thread ids. At the
-end of the list it also prints the total number of such threads.
+Produces a list of the currently known global @value{GDBN} thread ids.
+At the end of the list it also prints the total number of such
+threads.
This command is retained for historical reasons, the
@code{-thread-info} command should be used instead.
@subsubheading Synopsis
@smallexample
- -thread-select @var{threadnum}
+ -thread-select @var{thread-id}
@end smallexample
-Make @var{threadnum} the current thread. It prints the number of the new
-current thread, and the topmost frame for that thread.
+Make thread with global thread number @var{thread-id} the current
+thread. It prints the number of the new current thread, and the
+topmost frame for that thread.
This command is deprecated in favor of explicitly using the
@samp{--thread} option to each command.
The identifier that the target uses to refer to the Ada task.
@item thread-id
-The identifier of the thread corresponding to the Ada task.
+The global thread identifier of the thread corresponding to the Ada
+task.
This field should always exist, as Ada tasks are always implemented
on top of a thread. But if @value{GDBN} cannot find this corresponding
@item thread-id
If a variable object is bound to a specific thread, then this is the
-thread's identifier.
+thread's global identifier.
@item has_more
For a dynamic varobj, this indicates whether there appear to be any
If values were requested, this is the value.
@item thread-id
-If this variable object is associated with a thread, this is the thread id.
-Otherwise this result is not present.
+If this variable object is associated with a thread, this is the
+thread's global thread id. Otherwise this result is not present.
@item frozen
If the variable object is frozen, this variable will be present with a value of 1.
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