O Que São Threads de Processo?
You may have heard the terms single-threaded and multi-threaded. Threads are units of execution within a process and are often called "lightweight processes." While processes operate with their own isolated system resources, threads within the same process can share these resources, such as memory. This shared-resource model makes communication between threads much faster and more efficient than communication between separate processes.
Single-Threaded vs. Multi-Threaded
Every process has at least one thread. A process with only one thread is called single-threaded, while a process with more than one is multi-threaded.
For example, when you use a modern text editor, it might run as a single process. However, within that process, one thread could be managing your keyboard input, while another thread runs in the background to perform spell-checking or auto-saving. This concurrent execution makes the application feel more responsive. Using multiple threads is often more efficient than launching multiple processes for related tasks.
How to Show Threads with ps
To inspect running processes and their threads, you can use the ps command. While ps has many options, a common way to show threads is with the m flag.
pete@icebox:~$ ps m
PID TTY STAT TIME COMMAND
2207 pts/2 - 0:01 bash
- - Ss 0:01 -
5252 pts/2 - 0:00 ps m
- - R+ 0:00 -Interpreting the Output
In the output above, the lines with a PID (Process ID) represent the main process. The lines directly underneath, which have a dash (-) instead of a PID, represent the threads belonging to that process. In this example, both the bash and ps m processes are single-threaded, as each has only one main thread listed.