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4.10 Debugging Programs with Multiple Threads
In some operating systems, such as GNU/Linux and Solaris, a single programmay have more than one thread of execution. The precise semanticsof threads differ from one operating system to another, but in generalthe threads of a single program are akin to multiple processes—exceptthat they share one address space (that is, they can all examine andmodify the same variables). On the other hand, each thread has its ownregisters and execution stack, and perhaps private memory.
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So, if you want to debug C/C code in Eclipse CDT on the Mac, you must install GDB. 1 Here is the procedure that worked for me. 2 Others have reported issues with this, so please do let me know in the comments if it doesn't work for you. Install and Use GNU Command Line Tools on macOS/OS X. The reason is that macOS/Mac OS X uses the BSD version command line tools. Gdb, etc.) is that the new GPLv3 doesn’t allow Apple to do so, while GPLv2 is fine with this behavior. After many GNU projects upgraded to GPL v3, Apple won’t be able to bundle them any more. After installing gdb from homebrew (via $ brew install gdb), I followed these instructions to give gdb permissions to attach to a process. When I got to the step that runs the command: $ codesign -. Mac OS X version 10.14.4. GDB version 8.3 (via homebrew) Added my user to the developer group; didn't help. After installing gdb from homebrew (via $ brew install gdb), I followed these instructions to give gdb permissions to attach to a process. When I got to the step that runs the command: $ codesign -entitlements gdb-entitlement.xml -fs gdb-cert $(which gdb) I get the following error, with an exit code of 1: /usr/local/bin/gdb.
Oct 31, 2018 This document explains how to debug Mozilla-derived applications such as Firefox, Thunderbird, and SeaMonkey on macOS using Xcode. If you want to debug from the terminal see Debugging Mozilla with lldb. For specific information on a way to.
GDB provides these facilities for debugging multi-threadprograms:
The GDB thread debugging facility allows you to observe allthreads while your program runs—but whenever GDB takescontrol, one thread in particular is always the focus of debugging.This thread is called the current thread. Debugging commands showprogram information from the perspective of the current thread.
Whenever GDB detects a new thread in your program, it displaysthe target system’s identification for the thread with a message in theform ‘[New systag]’, where systag is a thread identifierwhose form varies depending on the particular system. For example, onGNU/Linux, you might see
when GDB notices a new thread. In contrast, on other systems,the systag is simply something like ‘process 368’, with nofurther qualifier.
For debugging purposes, GDB associates its own thread number—always a single integer—with each thread of an inferior. Thisnumber is unique between all threads of an inferior, but not uniquebetween threads of different inferiors.
You can refer to a given thread in an inferior using the qualifiedinferior-num.thread-num syntax, also known asqualified thread ID, with inferior-num being the inferiornumber and thread-num being the thread number of the giveninferior. For example, thread
2.3 refers to thread number 3 ofinferior 2. If you omit inferior-num (e.g., thread 3 ),then GDB infers you’re referring to a thread of the currentinferior.
Until you create a second inferior, GDB does not show theinferior-num part of thread IDs, even though you can always usethe full inferior-num.thread-num form to refer to threadsof inferior 1, the initial inferior.
Some commands accept a space-separated thread ID list asargument. A list element can be: Mac screensavers.
For example, if the current inferior is 1, and inferior 7 has onethread with ID 7.1, the thread list ‘1 2-3 4.5 6.7-9 7.*’includes threads 1 to 3 of inferior 1, thread 5 of inferior 4, threads7 to 9 of inferior 6 and all threads of inferior 7. That is, inexpanded qualified form, the same as ‘1.1 1.2 1.3 4.5 6.7 6.8 6.97.1’.
In addition to a per-inferior number, each thread is alsoassigned a unique global number, also known as globalthread ID, a single integer. Unlike the thread number component ofthe thread ID, no two threads have the same global ID, even whenyou’re debugging multiple inferiors.
From GDB’s perspective, a process always has at least onethread. In other words, GDB assigns a thread number to theprogram’s “main thread” even if the program is not multi-threaded.
The debugger convenience variables ‘$_thread’ and‘$_gthread’ contain, respectively, the per-inferior thread numberand the global thread number of the current thread. You may find thisuseful in writing breakpoint conditional expressions, command scripts,and so forth. See Convenience Variables, forgeneral information on convenience variables.
If GDB detects the program is multi-threaded, it augments theusual message about stopping at a breakpoint with the ID and name ofthe thread that hit the breakpoint.
Likewise when the program receives a signal:
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