Obtain a read lock on rw_lock. If another thread currently holds
the write lock on rw_lock or blocks waiting for it, the current
thread will block. Read locks can be taken recursively.
It is implementation-defined how many threads are allowed to
hold read locks on the same lock simultaneously.
Since 2.32
Obtain a read lock on rw_lock. If another thread currently holds the write lock on rw_lock or blocks waiting for it, the current thread will block. Read locks can be taken recursively. It is implementation-defined how many threads are allowed to hold read locks on the same lock simultaneously. Since 2.32