1. 默認設置下,在調試多進程程序時GDB只會調試主進程。但是GDB(>V7.0)支持多進程的
分別以及同時
調試,換句話說,GDB可以同時調試多個程序。只需要設置follow-fork-mode(默認值:parent)和detach-on-fork(默認值:on)即可。
? ? ? ? follow-fork-mode? detach-on-fork? ? 說明
? 設置方法:set follow-fork-mode [parent|child] ? set detach-on-fork [on|off]
? ? 查詢正在調試的進程:info inferiors
? ? 切換調試的進程: inferior <infer number>
? ? 添加新的調試進程: add-inferior [-copies n] [-exec executable] ,可以用file executable來分配給inferior可執行文件。
? ? 其他:remove-inferiors infno, detach inferior
2. GDB默認支持調試多線程,跟主線程,子線程block在create thread。
? ? 查詢線程:info threads
? ? 切換調試線程:thread <thread number>
例程:
調試:
1. 調試主進程,block子進程。
parent? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? on? ? ? ? ? ? ? ? ? ? ? ? ? ? 只調試主進程(GDB默認)
child? ? ? ? ? ? ? ? ? ? ? ? ? on? ? ? ? ? ? ? ? ? ? ? ? ? ? 只調試子進程
parent? ? ? ? ? ? ? ? ? ? ? ? ? ? ? off? ? ? ? ? ? ? ? ? ? ? ? ? 同時調試兩個進程,gdb跟主進程,子進程block在fork位置
child? ? ? ? ? ? ? ? ? ? ? ? ? ? ? off ? ? ? ? ? ? ? ? ? ? ? ? 同時調試兩個進程,gdb跟子進程,主進程block在fork位置
?child?
parent?
child?
?
?
?
?
2. GDB默認支持調試多線程,跟主線程,子線程block在create thread。
?
?
例程:
#include <stdio.h>
#include <pthread.h>
void processA();
void processB();
void * processAworker(void *arg);
int main(int argc, const char *argv[])
? {
? int pid;
? pid = fork();
? if(pid != 0)
? ? ? processA();
? else
? ? ? processB();
? return 0;
? }
void processA()
? {
? pid_t pid = getpid();
? char prefix[] = "ProcessA: ";
? char tprefix[] = "thread ";
? int tstatus;
? pthread_t pt;
? printf("%s%lu %s\n", prefix, pid, "step1");
? tstatus = pthread_create(&pt, NULL, processAworker, NULL);
? if( tstatus != 0 )
? ? ? {
? ? ? printf("ProcessA: Can not create new thread.");
? ? ? }
?
? processAworker(NULL);
? sleep(1);
? }
void * processAworker(void *arg)
? {
? pid_t pid = getpid();
? pthread_t tid = pthread_self();
? char prefix[] = "ProcessA: ";
? char tprefix[] = "thread ";
? printf("%s%lu %s%lu %s\n", prefix, pid, tprefix, tid, "step2");
? printf("%s%lu %s%lu %s\n", prefix, pid, tprefix, tid, "step3");
? return NULL;
? }
void processB()
? {
? pid_t pid = getpid();
? char prefix[] = "ProcessB: ";
? printf("%s%lu %s\n", prefix, pid, "step1");
? printf("%s%lu %s\n", prefix, pid, "step2");
? printf("%s%lu %s\n", prefix, pid, "step3");
? }
輸出:
#include <pthread.h>
void processA();
void processB();
void * processAworker(void *arg);
int main(int argc, const char *argv[])
?
?
?
?
?
?
?
?
?
void processA()
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
?
void * processAworker(void *arg)
?
?
?
?
?
?
?
?
?
void processB()
?
?
?
?
?
?
?
[cnwuwil@centos c-lab]$ ./test
ProcessA: 802 step1
ProcessB: 803 step1
ProcessB: 803 step2
ProcessB: 803 step3
ProcessA: 802 thread 3077555904 step2
ProcessA: 802 thread 3077555904 step3
ProcessA: 802 thread 3077553008 step2
ProcessA: 802 thread 3077553008 step3
ProcessB: 803 step1
ProcessB: 803 step2
ProcessB: 803 step3
ProcessA: 802 thread 3077555904 step2
ProcessA: 802 thread 3077555904 step3
ProcessA: 802 thread 3077553008 step2
ProcessA: 802 thread 3077553008 step3
調試:
1. 調試主進程,block子進程。
(gdb) set detach-on-fork off
(gdb) show detach-on-fork
Whether gdb will detach the child of a fork is off.
(gdb) catch fork
Catchpoint 1 (fork)
(gdb) r
[Thread debugging using libthread_db enabled]
Catchpoint 1 (forked process 3475), 0x00110424 in __kernel_vsyscall ()
Missing separate debuginfos, use: debuginfo-install glibc-2.12-1.47.el6.i686
(gdb) break test.c:14
Breakpoint 2 at 0x8048546: file test.c, line 14.
(gdb) cont
[New process 3475]
[Thread debugging using libthread_db enabled]
Breakpoint 2, main (argc=1, argv=0xbffff364) at test.c:14
Missing separate debuginfos, use: debuginfo-install glibc-2.12-1.47.el6.i686
(gdb) info inferiors
? Num? Description? ? ? ? ? ? Executable? ? ? ? ? ? ?
? 2? ? ? process 3475? ? ? ? ? /home/cnwuwil/labs/c-lab/test
* 1? ? ? process 3472? ? ? ? ? /home/cnwuwil/labs/c-lab/test
2. 切換到子進程:
(gdb) show detach-on-fork
Whether gdb will detach the child of a fork is off.
(gdb) catch fork
Catchpoint 1 (fork)
(gdb) r
[Thread debugging using libthread_db enabled]
Catchpoint 1 (forked process 3475), 0x00110424 in __kernel_vsyscall ()
Missing separate debuginfos, use: debuginfo-install glibc-2.12-1.47.el6.i686
(gdb) break test.c:14
Breakpoint 2 at 0x8048546: file test.c, line 14.
(gdb) cont
[New process 3475]
[Thread debugging using libthread_db enabled]
Breakpoint 2, main (argc=1, argv=0xbffff364) at test.c:14
Missing separate debuginfos, use: debuginfo-install glibc-2.12-1.47.el6.i686
(gdb) info inferiors
?
?
* 1?
(gdb) inferior 2
[Switching to inferior 2 [process 3475] (/home/cnwuwil/labs/c-lab/test)]
[Switching to thread 2 (Thread 0xb7fe86c0 (LWP 3475))]
#0? 0x00110424 in ?? ()
(gdb) info inferiors
? Num? Description? ? ? ? ? ? Executable? ? ? ? ? ? ?
* 2? ? ? process 3475? ? ? ? ? /home/cnwuwil/labs/c-lab/test
? 1? ? ? process 3472? ? ? ? ? /home/cnwuwil/labs/c-lab/test
(gdb) inferior 1
[Switching to inferior 1 [process 3472] (/home/cnwuwil/labs/c-lab/test)]
[Switching to thread 1 (Thread 0xb7fe86c0 (LWP 3472))]
#0? main (argc=1, argv=0xbffff364) at test.c:14
(gdb) info inferiors
? Num? Description? ? ? ? ? ? Executable? ? ? ? ? ? ?
? 2? ? ? process 3475? ? ? ? ? /home/cnwuwil/labs/c-lab/test
* 1? ? ? process 3472? ? ? ? ? /home/cnwuwil/labs/c-lab/test
3. 設斷點繼續調試主進程,主進程產生兩個子線程:
[Switching to inferior 2 [process 3475] (/home/cnwuwil/labs/c-lab/test)]
[Switching to thread 2 (Thread 0xb7fe86c0 (LWP 3475))]
#0?
(gdb) info inferiors
?
* 2?
?
(gdb) inferior 1
[Switching to inferior 1 [process 3472] (/home/cnwuwil/labs/c-lab/test)]
[Switching to thread 1 (Thread 0xb7fe86c0 (LWP 3472))]
#0?
(gdb) info inferiors
?
?
* 1?
(gdb) break test.c:50
Breakpoint 3 at 0x804867d: file test.c, line 50. (2 locations)
(gdb) cont
ProcessA: 3472 step1
[New Thread 0xb7fe7b70 (LWP 3562)]
ProcessA: 3472 thread 3086911168 step2
Breakpoint 3, processAworker (arg=0x0) at test.c:50
(gdb) info inferiors
? Num? Description? ? ? ? ? ? Executable? ? ? ? ? ? ?
? 2? ? ? process 3475? ? ? ? ? /home/cnwuwil/labs/c-lab/test
* 1? ? ? process 3472? ? ? ? ? /home/cnwuwil/labs/c-lab/test
(gdb) info threads
? 3 Thread 0xb7fe7b70 (LWP 3562)? 0x00110424 in __kernel_vsyscall ()
? 2 Thread 0xb7fe86c0 (LWP 3475)? 0x00110424 in ?? ()
* 1 Thread 0xb7fe86c0 (LWP 3472)? processAworker (arg=0x0) at test.c:50
4. 切換到主進程中的子線程,注意:線程2為前面產生的子進程
Breakpoint 3 at 0x804867d: file test.c, line 50. (2 locations)
(gdb) cont
ProcessA: 3472 step1
[New Thread 0xb7fe7b70 (LWP 3562)]
ProcessA: 3472 thread 3086911168 step2
Breakpoint 3, processAworker (arg=0x0) at test.c:50
(gdb) info inferiors
?
?
* 1?
(gdb) info threads
?
?
* 1 Thread 0xb7fe86c0 (LWP 3472)?
(gdb) thread 3
[Switching to thread 3 (Thread 0xb7fe7b70 (LWP 3562))]#0? 0x00110424 in __kernel_vsyscall ()
(gdb) cont
ProcessA: 3472 thread 3086911168 step3
ProcessA: 3472 thread 3086908272 step2
[Switching to Thread 0xb7fe7b70 (LWP 3562)]
Breakpoint 3, processAworker (arg=0x0) at test.c:50
(gdb) info threads
* 3 Thread 0xb7fe7b70 (LWP 3562)? processAworker (arg=0x0) at test.c:50
? 2 Thread 0xb7fe86c0 (LWP 3475)? 0x00110424 in ?? ()
? 1 Thread 0xb7fe86c0 (LWP 3472)? 0x00110424 in __kernel_vsyscall ()
(gdb) thread 1
[Switching to thread 3 (Thread 0xb7fe7b70 (LWP 3562))]#0?
(gdb) cont
ProcessA: 3472 thread 3086911168 step3
ProcessA: 3472 thread 3086908272 step2
[Switching to Thread 0xb7fe7b70 (LWP 3562)]
Breakpoint 3, processAworker (arg=0x0) at test.c:50
(gdb) info threads
* 3 Thread 0xb7fe7b70 (LWP 3562)?
?
?
(gdb) thread 1