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Why does the kernel need PID to get process information?
Every time a user or the system (Linux) launches a program, the kernel will create a process. The kernel identifies each process using a process ID (PID), a every instance of process must have a unique PID from other processes which is assigned when the process is invoked, to avoid any execution errors.
Does thread have PID?
In the kernel, each thread has its own ID, called a PID, although it would possibly make more sense to call this a TID, or thread ID, and they also have a TGID (thread group ID) which is the PID of the first thread that was created when the process was created.
What is PID in kernel?
In computing, the process identifier (a.k.a. process ID or PID) is a number used by most operating system kernels—such as those of Unix, macOS and Windows—to uniquely identify an active process.
Do threads have the same process ID?
On Linux, threads created by pthread_create also receive a thread ID. The thread ID of the initial (main) thread is the same as the process ID of the entire process. Thread IDs for subsequently created threads are distinct. You can get the process ID of a process by calling getpid .
What’s the difference between threads and processes?
A process is a collection of code, memory, data and other resources. A thread is a sequence of code that is executed within the scope of the process. You can (usually) have multiple threads executing concurrently within the same process.
Does Linux have kernel threads?
Linux has a unique implementation of threads. To the Linux kernel, there is no concept of a thread. The Linux kernel does not provide any special scheduling semantics or data structures to represent threads. Instead, a thread is merely a process that shares certain resources with other processes.
How does the kernel distinguish between thread and TGID?
In the kernel, each thread has it’s own ID, called a PID (although it would possibly make more sense to call this a TID, or thread ID) and they also have a TGID (thread group ID) which is the PID of the thread that started the whole process.
Can a thread have the same PID as a kernel?
3 Answers 3. The four threads will have the same PID but only when viewed from above. What you (as a user) call a PID is not what the kernel (looking from below) calls a PID.
How are Linux kernel threads really kernel processes?
There is absolutely no difference between a thread and a process on Linux. If you look at clone (2) you will see a set of flags that determine what is shared, and what is not shared, between the threads. Classic processes are just threads that share nothing; you can share what components you want under Linux.
Which is the PID of the first thread?
In the kernel, each thread has its own ID, called a PID, although it would possibly make more sense to call this a TID, or thread ID, and they also have a TGID (thread group ID) which is the PID of the first thread that was created when the process was created.