[#BloombergLP-bdlmt-ThreadPool]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlmt.adoc[bdlmt]::ThreadPool
:relfileprefix: ../../
:mrdocs:

This class implements a thread pool used for concurrently executing multiple user‐defined functions ("jobs").

== Synopsis

Declared in `<bdlmt_threadpool.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
class ThreadPool;
----

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlmt/ThreadPool/Job.adoc[`Job`] 
| Callable type representing a job to be executed by the thread pool.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlmt/ThreadPool/2constructor-0e.adoc[`ThreadPool`]         [.small]#[constructor]#
| Constructors
| xref:BloombergLP/bdlmt/ThreadPool/2destructor.adoc[`~ThreadPool`] [.small]#[destructor]#
| Call `shutdown()` and destroy this thread pool.
| xref:BloombergLP/bdlmt/ThreadPool/drain.adoc[`drain`] 
| Disable queuing on this thread pool and wait until all pending jobs complete. Use `start` to re‐enable queuing.
| xref:BloombergLP/bdlmt/ThreadPool/enabled.adoc[`enabled`] 
| Return the state (enabled or not) of the thread pool.
| xref:BloombergLP/bdlmt/ThreadPool/enqueueJob-0e.adoc[`enqueueJob`] 
| `enqueueJob` overloads
| xref:BloombergLP/bdlmt/ThreadPool/maxIdleTime.adoc[`maxIdleTime`] 
| Return the amount of time (in milliseconds) a thread remains idle before being shut down when there are more than min threads started.
| xref:BloombergLP/bdlmt/ThreadPool/maxIdleTimeInterval.adoc[`maxIdleTimeInterval`] 
| Return the amount of time a thread remains idle before being shut down when there are more than min threads started.
| xref:BloombergLP/bdlmt/ThreadPool/maxThreads.adoc[`maxThreads`] 
| Return the maximum number of threads that are allowed to be running at given time.
| xref:BloombergLP/bdlmt/ThreadPool/minThreads.adoc[`minThreads`] 
| Return the minimum number of threads that must be started at any given time.
| xref:BloombergLP/bdlmt/ThreadPool/numActiveThreads.adoc[`numActiveThreads`] 
| Return the number of threads that are currently processing a job.
| xref:BloombergLP/bdlmt/ThreadPool/numPendingJobs.adoc[`numPendingJobs`] 
| Return the number of jobs that are currently queued, but not yet being processed.
| xref:BloombergLP/bdlmt/ThreadPool/numWaitingThreads.adoc[`numWaitingThreads`] 
| Return the number of threads that are currently waiting for a job.
| xref:BloombergLP/bdlmt/ThreadPool/percentBusy.adoc[`percentBusy`] 
| Return the percentage of wall time spent executing jobs.
| xref:BloombergLP/bdlmt/ThreadPool/resetPercentBusy.adoc[`resetPercentBusy`] 
| Report thread‐pool busy percentage since last reset.
| xref:BloombergLP/bdlmt/ThreadPool/shutdown.adoc[`shutdown`] 
| Disable queuing on this thread pool, cancel all queued jobs, and shut down all processing threads (after all active jobs complete).
| xref:BloombergLP/bdlmt/ThreadPool/start.adoc[`start`] 
| Enable queuing and start processing threads.
| xref:BloombergLP/bdlmt/ThreadPool/stop.adoc[`stop`] 
| Disable queuing on this thread pool and wait until all pending jobs complete, then shut down all processing threads.
| xref:BloombergLP/bdlmt/ThreadPool/threadFailures.adoc[`threadFailures`] 
| Return the number of times that thread creation failed.
| xref:BloombergLP/bdlmt/ThreadPool/2conversion.adoc[`operator BloombergLP::bslmf::NestedTraitDeclaration<ThreadPool, UsesBslmaAllocator>`] 
| Declare that this type uses a `bslma` allocator.
|===


== Friends

[cols="1,4"]
|===
| Name| Description
| `xref:BloombergLP/bdlmt/ThreadPoolEntry.adoc[BloombergLP::bdlmt::ThreadPoolEntry]`
| Entry point for processing threads.
|===


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