Thread Information (Sun Studio 12 Update 1: Debugging a Program With dbx)

Sun Studio 12 Update 1: Debugging a Program With dbx

Thread Information

The following thread information is available in dbx:

(dbx) threads
    t@1 a l@1  ?()  running   in main()
    t@2      ?() asleep on 0xef751450  in_swtch()
    t@3 b l@2  ?()  running in sigwait()
    t@4     consumer()  asleep on 0x22bb0 in _lwp_sema_wait()
  *>t@5 b l@4 consumer()  breakpoint     in Queue_dequeue()
    t@6 b l@5 producer()     running       in _thread_start()
(dbx)

For native code, each line of information is composed of the following:

The * (asterisk) indicates that an event requiring user attention has occurred in this thread. Usually this is a breakpoint.

An ’o’ instead of an asterisk indicates that a dbx internal event has occurred.
The > (arrow) denotes the current thread.
t@number, the thread id, refers to a particular thread. The number is the thread_t value passed back by thr_create.
b l@number or a l@number means the thread is bound to or active on the designated LWP, meaning the thread is actually runnable by the operating system.
The “Start function” of the thread as passed to thr_create. A ?() means that the start function is not known.
The thread state (see Table 11–1 for descriptions of the thread states).
The function that the thread is currently executing.

For Java code, each line of information is composed of the following:

t@number, a dbx-style thread ID
The thread state (See Table 11–1 for descriptions of the thread states.)
The thread name in single quotation marks
A number indicating the thread priority

Table 11–1 Thread and LWP States


Thread and LWP States	Description
suspended	The thread has been explicitly suspended.
runnable	The thread is runnable and is waiting for an LWP as a computational resource.
zombie	When a detached thread exits `(thr_exit))`, it is in a zombie state until it has rejoined through the use of `thr_join(). THR_DETACHED` is a flag specified at thread creation time `(thr_create())`. A non-detached thread that exits is in a zombie state until it has been reaped.
asleep on `syncobj`	Thread is blocked on the given synchronization object. Depending on what level of support `libthread` and `libthread_db` provide, `syncobj` might be as simple as a hexadecimal address or something with more information content.
active	The thread is active on an LWP, but `dbx` cannot access the LWP.
unknown	`dbx` cannot determine the state.
`lwpstate`	A bound or active thread state has the state of the LWP associated with it.
running	LWP was running but was stopped in synchrony with some other LWP.
syscall `num`	LWP stopped on an entry into the given system call #.
syscall return `num`	LWP stopped on an exit from the given system call #.
job control	LWP stopped due to job control.
LWP suspended	LWP is blocked in the kernel.
single stepped	LWP has just completed a single step.
breakpoint	LWP has just hit a breakpoint.
fault `num`	LWP has incurred the given fault #.
signal `name`	LWP has incurred the given signal.
process sync	The process to which this LWP belongs has just started executing.
LWP death	LWP is in the process of exiting.