Package groovy.concurrent

Class ConcurrentConfig

java.lang.Object

groovy.concurrent.ConcurrentConfig

public final class ConcurrentConfig
extends Object

Central configuration for Groovy's concurrent and parallel features.

Configuration is resolved in order:

1. Programmatic overrides via setter methods
2. System properties (groovy.concurrent.poolsize, groovy.concurrent.virtual)
3. Sensible defaults (processors + 1, virtual threads on JDK 21+)

Inspired by GPars' GParsConfig and PoolUtils, modernised for virtual threads and the Pool abstraction.

Since:

6.0.0

See Also:

• Pool

Method Summary

Modifier and Type	Method	Description
static int	getDefaultParallelism()	Returns the default parallelism level.
static Pool	getDefaultPool()	Returns the global default pool.
static boolean	preferVirtualThreads()	Returns true if virtual threads should be preferred.
static void	setDefaultParallelism(int size)	Sets the default parallelism level programmatically.
static void	setDefaultPool(Pool pool)	Sets the global default pool.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

getDefaultParallelism

public static int getDefaultParallelism()

Returns the default parallelism level.

Checks (in order): programmatic override, system property groovy.concurrent.poolsize, then Runtime.availableProcessors() + 1 (following the GPars convention).

Returns:

the default pool size, always > 0

setDefaultParallelism

public static void setDefaultParallelism(int size)

Sets the default parallelism level programmatically. Pass 0 or a negative value to reset to the default.

Parameters:

size - the pool size, or ≤ 0 to reset

preferVirtualThreads

public static boolean preferVirtualThreads()

Returns true if virtual threads should be preferred.

Checks the system property groovy.concurrent.virtual (default: true on JDK 21+, false otherwise).

Returns:

whether to prefer virtual threads

getDefaultPool

public static Pool getDefaultPool()

Returns the global default pool. If none has been set, creates one based on current configuration: a virtual-thread pool if preferVirtualThreads() is true, otherwise a fixed pool sized by getDefaultParallelism().

Returns:

the default pool, never null

setDefaultPool

public static void setDefaultPool(Pool pool)

Sets the global default pool. Pass null to reset.

Parameters:

pool - the pool to use as default, or null to reset