Common configuration methods for using GDB to debug multi-threaded programs under Linux

Common configuration methods for using GDB to debug multi-threaded programs under Linux

Introduction:
In multi-threaded programming, debugging is an essential task. GDB is a powerful debugger that can help us locate and solve errors in multi-threaded programs. This article will introduce common configuration methods for using GDB to debug multi-threaded programs under Linux, and provide code examples, hoping to help readers better understand and use GDB.

1. Install GDB
First, we need to install GDB in the Linux system. Enter the following command in the terminal to complete the installation:

$ sudo apt-get install gdb

2. Compile multi-threaded program
Before debugging a multi-threaded program, we first need to write and compile a simple multi-threaded program. The following is the code of a sample program:

#include <stdio.h>
#include <pthread.h>

#define NUM_THREADS 5

void* thread_func(void* thread_id) {
    long tid = (long)thread_id;
    printf("Hello World! It's me, thread #%ld!
", tid);
    pthread_exit(NULL);
}

int main() {
    pthread_t threads[NUM_THREADS];
    int rc;
    long t;

    for (t = 0; t < NUM_THREADS; t++) {
        printf("In main: creating thread %ld
", t);
        rc = pthread_create(&threads[t], NULL, thread_func, (void*)t);

        if (rc) {
            printf("ERROR; return code from pthread_create() is %d
", rc);
            return -1;
        }
    }

    pthread_exit(NULL);
}

We save the above code to a file named multithread.c and compile it using the following command:

$ gcc -g -pthread -o multithread multithread.c

Among them, the -g option is used to add debugging information to the executable file, and the -pthread option is used to introduce the multi-thread library.

3. Start GDB debugging
After completing the compilation, we can use GDB to start debugging. Enter the following command in the terminal:

$ gdb multithread

4. Configure GDB debugging options
In GDB, there are some debugging options that can help us better debug multi-threaded programs. We can configure it by entering the following command:

1. Set the display thread number
   Enter the following command in GDB to set the display thread number:

(gdb) set print thread-events off

2. Set the display stack
   Enter the following command in GDB to set the display stack:

(gdb) set backtrace limit 10

3. Set the display thread information
   Enter the following command in GDB to set the display thread Information:

(gdb) show scheduling 

4. Set the code location for display thread execution
   Enter the following command in GDB to set the code location for display thread execution:

(gdb) set scheduler-locking on

5. Set breakpoints and monitoring points
During the debugging process, we can set breakpoints and monitoring points to control the execution flow of the program. The following are some commonly used command examples:

1. Set breakpoint
   Enter the following command in GDB to set a breakpoint:

(gdb) break function_name

2. Delete breakpoint Click
   Enter the following command in GDB to delete the breakpoint:

(gdb) delete breakpoints

3. Set monitoring point
   Enter the following command in GDB to set the monitoring point:

(gdb) watch variable_name

4. Delete monitoring points
   Enter the following command in GDB to delete monitoring points:

(gdb) delete watchpoints

6. Debugging multi-threaded programs
In GDB , we can use the following command to debug a multi-threaded program:

1. Start the program
   Enter the following command in GDB to start the program:

(gdb) run

2. Pause the program
   Enter the following command in GDB to pause the executing program:

(gdb) Ctrl+C

3. List all threads
   Enter the following command in GDB to list all Thread:

(gdb) info threads

4. Switch to the specified thread
   Enter the following command in GDB to switch to the specified thread:

(gdb) thread thread_id

5. Continue execution Program
   Enter the following command in GDB to continue executing the program:

(gdb) continue

7. Summary
This article introduces the common configuration methods for using GDB to debug multi-threaded programs under Linux, and Comes with code examples. By properly configuring debugging options and using corresponding commands, we can well control and locate problems in multi-threaded programs and improve debugging efficiency and accuracy. I hope this article can help readers in multi-thread debugging and inspire more learning and practice.

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