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# Process
## NAME
process - Process abstraction
## SYNOPSIS
A zircon process is an instance of a program in the traditional
sense: a set of instructions which will be executed by one or more
threads, along with a collection of resources.
## DESCRIPTION
The process object is a container of the following resources:
+ [Handles](/docs/concepts/kernel/handles.md)
+ [Virtual Memory Address Regions](vm_address_region.md)
+ [Threads](thread.md)
In general, it is associated with code which it is executing until it is
forcefully terminated or the program exits.
Processes are owned by [jobs](job.md) and allow an application that is
composed by more than one process to be treated as a single entity, from the
perspective of resource and permission limits, as well as lifetime control.
### Lifetime
A process is created via [`zx_process_create()`] and its execution begins with
[`zx_process_start()`].
The process stops execution when:
+ the last thread is terminated or exits
+ the process calls [`zx_process_exit()`]
+ the parent job terminates the process
+ the parent job is destroyed
The call to [`zx_process_start()`] cannot be issued twice. New threads cannot
be added to a process that was started and then its last thread has exited.
## SYSCALLS
- [`zx_process_create()`] - create a new process within a job
- [`zx_process_read_memory()`] - read from a process's address space
- [`zx_process_start()`] - cause a new process to start executing
- [`zx_process_write_memory()`] - write to a process's address space
- [`zx_process_exit()`] - exit the current process
<br>
- [`zx_job_create()`] - create a new job within a parent job
<br>
- [`zx_task_create_exception_channel()`] - listen for task exceptions
<br>
- [`zx_vmar_map()`] - Map memory into an address space range
- [`zx_vmar_protect()`] - Change permissions on an address space range
- [`zx_vmar_unmap()`] - Unmap memory from an address space range
[`zx_job_create()`]: /docs/reference/syscalls/job_create.md
[`zx_process_create()`]: /docs/reference/syscalls/process_create.md
[`zx_process_exit()`]: /docs/reference/syscalls/process_exit.md
[`zx_process_read_memory()`]: /docs/reference/syscalls/process_read_memory.md
[`zx_process_start()`]: /docs/reference/syscalls/process_start.md
[`zx_process_write_memory()`]: /docs/reference/syscalls/process_write_memory.md
[`zx_task_create_exception_channel()`]: /docs/reference/syscalls/task_create_exception_channel.md
[`zx_vmar_map()`]: /docs/reference/syscalls/vmar_map.md
[`zx_vmar_protect()`]: /docs/reference/syscalls/vmar_protect.md
[`zx_vmar_unmap()`]: /docs/reference/syscalls/vmar_unmap.md