How do I add a thread to GDB?
Just run a program with s few threads, run gdb and before running attach PROCESS_PID run strace in another console. You must see ptrace (PTRACE_ATTACH) for each thread. Show activity on this post. ptrace PTRACE_ATTACH sends SIGSTOP to the process which suspends the whole process i.e. all threads.
How do I debug a thread?
By Freezing and Thawing threads (suspending and resuming), we can have control of the threads running during the debugging process….
- Insert a Breakpoint in the code.
- Run our application (press F5).
- Click on the Debug menu and choose the windows option then select Threads as shown in the following image.
How do you read a gdb backtrace?
To display the backtrace for several or all of the threads, use the command thread apply (see thread apply). For example, if you type thread apply all backtrace , GDB will display the backtrace for all the threads; this is handy when you debug a core dump of a multi-threaded program.
How do I debug a multi threaded program?
Debug the multithreaded app
- In the source code editor, look for one of the following code snippets: C# Copy.
- Left-click in the left gutter of the Thread.
- On the Debug menu, select Start Debugging (F5).
- In the source code editor, locate the line that contains the breakpoint.
What is thread debugging?
A thread is a sequence of instructions to which the operating system grants processor time. Every process that is running in the operating system consists of at least one thread.
How do I backtrace for all threads?
What is Libthread_db?
libthread_db is a library that provides support for monitoring and manipulating threads-related aspects of a multithreaded program. There are at least two processes involved, the controlling process and one or more target processes.
How does a backtrace work?
The backtrace shows the current function, then the function that called that, and so on, all the way back to main() . Each “stack frame” is the section of stack used by a particular function, so there’s one frame per function. Since the current function is main() , there is only one frame to show.
How do I test a concurrent code?
One good way to test this is to make sure you have access to a multi-cpu machine, then run your test for as long a time/with as many iterations as possible. For example if you have a multithreaded producer consumer algorithm, fill the queue with a good sized list and use 2x as many threads as you might in production.
Why is it hard to debug a multithreaded program?
Parallel processing using many threads can greatly improve program performance, but it may also make debugging more difficult because you’re tracking many threads. Multithreading can introduce new types of potential bugs.
How do I remove all breakpoints in GDB?
use delete command with no arguments; it can be abbreviated to del or d . Show activity on this post. I want to disable or remove all of them at once, or all except for one. Use disable (with no arguments) to disable all breakpoints, followed by enable N , where N is the breakpoint you want to keep.
What is a breakpoint in gdb?
Breakpoints are points in your code at which gdb will stop and allow executing other gdb commands. Set a breakpoint at the beginning of a function.
How do I delete a watchpoint in gdb?
Simply quit GDB, and all breakpoints and watchpoints will be gone. Or do (gdb) delete (without specifying a break point), and confirm that you want to delete all.
How do I apply a GDB command to all threads?
To apply a command to all threads, use thread apply all args . Whenever GDB stops your program, due to a breakpoint or a signal, it automatically selects the thread where that breakpoint or signal happened. GDB alerts you to the context switch with a message of the form ` [Switching to systag]’ to identify the thread.
What happens if my GDB does not support threads?
If your GDB does not support threads, these commands have no effect. For example, a system without thread support shows no output from `info threads’, and always rejects the thread command, like this: (gdb) info threads (gdb) thread 1 Thread ID 1 not known.
How does GDB select the thread where a breakpoint or signal occurs?
Whenever GDB stops your program, due to a breakpoint or a signal, it automatically selects the thread where that breakpoint or signal happened. GDB alerts you to the context switch with a message of the form `
What does $pdir mean in gdb?
A special entry ‘ $pdir ’ for ‘ libthread-db-search-path ’ refers to the directory from which libpthread was loaded in the inferior process. For any libthread_db library GDB finds in above directories, GDB attempts to initialize it with the current inferior process.