The size of the thread pool and the host operating system impact performance and processor utilization.
In general, Oracle recommends using one thread per processor or core for good performance in most cases. The actual optimal number of threads for a given application depends on many factors, and is best determined through experimental performance measurements using expected query load on production data.
If high performance is required, enable more than one thread. Determine the optimal number of threads through load testing of different configurations.
As a starting point, enable the following number of threads:
For example, consider a server with two hyperthreaded processors and sufficient disk resources and RAM, on which a high-performance application will be deployed. The appropriate starting point for such an architecture would be one MDEX Engine running multithreaded with 4 threads.
On Linux and Solaris, the MDEX Engine uses the
POSIX Thread Library,
Pthreads. You can examine the thread count using
standard tools, such as
top.
On Windows, the MDEX Engine uses native Windows threads. The thread count for an MDEX Engine can be examined in the Windows Task Manager in the Threads column.
Note
The number of threads listed may be greater than the value
specified for the
--threads flag; the additional threads that could be
listed are those that are used infrequently by processes that are not
CPU-intensive and represent internal maintenance tasks. All the CPU-intensive,
query processing-related threads are controlled by the
--threads flag.
