#include <db.h>

int
DB_ENV->set_thread_count(DB_ENV *dbenv, u_int32_t count);

int
DB_ENV->get_thread_count(DB_ENV *dbenv, u_int32_t *countp);

Declare an approximate number of threads in the database environment. The DB_ENV->set_thread_count method must be called prior to opening the database environment if the DB_ENV->failchk method will be used. The DB_ENV->set_thread_count method does not set the maximum number of threads but is used to determine memory sizing and the thread control block reclamation policy.

If a process has not configured an is_alive function from the DB_ENV->set_isalive method, and then attempts to join a database environment configured for failure checking with the DB_ENV->failchk, DB_ENV->set_thread_id, DB_ENV->set_isalive and DB_ENV->set_thread_count methods, the program may be unable to allocate a thread control block and fail to join the environment. This is true of the standalone Berkeley DB utility programs. To avoid problems when using the standalone Berkeley DB utility programs with environments configured for failure checking, incorporate the utility's functionality directly in the application, or call the DB_ENV->failchk method before running the utility.

The database environment's thread count may also be configured using the environment's DB_CONFIG file. The syntax of the entry in that file is a single line with the string "set_thread_count", one or more whitespace characters, and the thread count. Because the DB_CONFIG file is read when the database environment is opened, it will silently overrule configuration done before that time.

The DB_ENV->set_thread_count method configures operations performed using the specified DB_ENV handle, not all operations performed on the underlying database environment.

The DB_ENV->set_thread_count method may not be called after the DB_ENV->open method is called.

The DB_ENV->set_thread_count method returns a non-zero error value on failure and 0 on success.

• The count parameter is an approximate thread count for the database environment.

The DB_ENV->set_thread_count method may fail and return one of the following non-zero errors:

• If the method was called after DB_ENV->open was called; or if an invalid flag value or parameter was specified.

The DB_ENV->get_thread_count method returns the thread count.

The DB_ENV->get_thread_count method may be called at any time during the life of the application.

The DB_ENV->get_thread_count method returns a non-zero error value on failure and 0 on success.

• The DB_ENV->get_thread_count method returns the thread count in countp.