---
name: "__gnu_parallel::parallel_tag"
section: "3cxx"
platform: "linux"
package: "libstdc++-12-doc"
version: "12.4.0-5"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/__gnu_parallel::parallel_tag/3cxx"
---

# \_\_gnu\_parallel::parallel\_tag(3cxx)

Recommends parallel execution at compile time, optionally using a user-specified number of threads.

## NAME

\_\_gnu\_parallel::parallel\_tag - Recommends parallel execution at compile time, optionally using a user-specified number of threads.

## SYNOPSIS

`#include <tags.h>`

Inherited by **\_\_gnu\_parallel::balanced\_quicksort\_tag**, **\_\_gnu\_parallel::balanced\_tag**, **\_\_gnu\_parallel::default\_parallel\_tag**, **\_\_gnu\_parallel::exact\_tag**, **\_\_gnu\_parallel::multiway\_mergesort\_exact\_tag**, **\_\_gnu\_parallel::multiway\_mergesort\_sampling\_tag**, **\_\_gnu\_parallel::multiway\_mergesort\_tag**, **\_\_gnu\_parallel::omp\_loop\_static\_tag**, **\_\_gnu\_parallel::omp\_loop\_tag**, **\_\_gnu\_parallel::quicksort\_tag**, **\_\_gnu\_parallel::sampling\_tag**, and **\_\_gnu\_parallel::unbalanced\_tag**.

### Public Member Functions

**parallel\_tag** ()\
 Default constructor. Use default number of threads.  **parallel\_tag** (**\_ThreadIndex** \_\_num\_threads)\
 Default constructor. Recommend number of threads to use.  **\_ThreadIndex** **\_\_get\_num\_threads** ()\
 Find out desired number of threads.  void **set\_num\_threads** (**\_ThreadIndex** \_\_num\_threads)\
 Set the desired number of threads.

## Detailed Description

Recommends parallel execution at compile time, optionally using a user-specified number of threads.

## Constructor & Destructor Documentation

### \_\_gnu\_parallel::parallel\_tag::parallel\_tag ()` [inline]`

Default constructor. Use default number of threads.

### \_\_gnu\_parallel::parallel\_tag::parallel\_tag (\_ThreadIndex \_\_num\_threads)` [inline]`

Default constructor. Recommend number of threads to use.

**Parameters**

*\_\_num\_threads* Desired number of threads.

## Member Function Documentation

### \_ThreadIndex \_\_gnu\_parallel::parallel\_tag::\_\_get\_num\_threads ()` [inline]`

Find out desired number of threads.

**Returns**

Desired number of threads.

Referenced by **\_\_gnu\_parallel::\_\_parallel\_sort()**, **\_\_gnu\_parallel::\_\_parallel\_sort()**, **\_\_gnu\_parallel::\_\_parallel\_sort()**, **\_\_gnu\_parallel::\_\_parallel\_sort()**, **\_\_gnu\_parallel::\_\_parallel\_sort()**, **\_\_gnu\_parallel::\_\_parallel\_sort()**, and **\_\_gnu\_parallel::\_\_parallel\_sort()**.

### void \_\_gnu\_parallel::parallel\_tag::set\_num\_threads (\_ThreadIndex \_\_num\_threads)` [inline]`

Set the desired number of threads.

**Parameters**

*\_\_num\_threads* Desired number of threads.

## Author

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