[#BloombergLP-bslmt-ReaderWriterMutexImpl-lockRead]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslmt.adoc[bslmt]::xref:BloombergLP/bslmt/ReaderWriterMutexImpl.adoc[ReaderWriterMutexImpl]::lockRead
:relfileprefix: ../../../
:mrdocs:

Lock this reader‐writer mutex for reading.

== Synopsis

Declared in `<bslmt_readerwritermuteximpl.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
void
lockRead();
----

== Description

If there are no active or pending write locks, lock this mutex for reading and return immediately. Otherwise, block until the read lock on this mutex is acquired. Use `unlockRead` or `unlock` to release the lock on this mutex. The behavior is undefined if this method is called from a thread that already has a lock on this mutex.


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