main/syscalls/thread_create.md

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# zx_thread_create

## Summary

Create a thread.

## Declaration

```c
#include <zircon/syscalls.h>

zx_status_t zx_thread_create(zx_handle_t process,
                             const char* name,
                             size_t name_size,
                             uint32_t options,
                             zx_handle_t* out);
```

## Description

`zx_thread_create()` creates a thread within the specified process.

Upon success a handle for the new thread is returned.  The thread
will not start executing until [`zx_thread_start()`] is called.

*name* is silently truncated to a maximum of `ZX_MAX_NAME_LEN-1` characters.

Thread handles may be waited on and will assert the signal
`ZX_THREAD_TERMINATED` when the thread stops executing (due to
[`zx_thread_exit()`] being called).

*process* is the controlling [process object](/docs/reference/kernel_objects/process.md) for the
new thread, which will become a child of that process.

For thread lifecycle details see [thread object](/docs/reference/kernel_objects/thread.md).

## Rights

*process* must be of type `ZX_OBJ_TYPE_PROCESS` and have `ZX_RIGHT_MANAGE_THREAD`.

## Return value

On success, `zx_thread_create()` returns `ZX_OK` and a handle (via *out*)
to the new thread.  In the event of failure, a negative error value is
returned.

## Errors

`ZX_ERR_BAD_HANDLE`  *process* is not a valid handle.

`ZX_ERR_WRONG_TYPE`  *process* is not a process handle.

`ZX_ERR_ACCESS_DENIED`  *process* does not have the `ZX_RIGHT_MANAGE_THREAD` right.

`ZX_ERR_INVALID_ARGS`  *name* or *out* was an invalid pointer, or *options* was
non-zero.

`ZX_ERR_NO_MEMORY`  Failure due to lack of memory.
There is no good way for userspace to handle this (unlikely) error.
In a future build this error will no longer occur.

## See also

 - [`zx_handle_close()`]
 - [`zx_handle_duplicate()`]
 - [`zx_object_wait_async()`]
 - [`zx_object_wait_many()`]
 - [`zx_object_wait_one()`]
 - [`zx_thread_exit()`]
 - [`zx_thread_start()`]

[`zx_handle_close()`]: handle_close.md
[`zx_handle_duplicate()`]: handle_duplicate.md
[`zx_object_wait_async()`]: object_wait_async.md
[`zx_object_wait_many()`]: object_wait_many.md
[`zx_object_wait_one()`]: object_wait_one.md
[`zx_thread_exit()`]: thread_exit.md
[`zx_thread_start()`]: thread_start.md