DbEnv::set_mp_max_openfd()
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## DbEnv::set_mp_max_openfd()

    #include <db_cxx.h>

    int
    DbEnv::set_mp_max_openfd(int maxopenfd);

The `DbEnv::set_mp_max_openfd()` method limits the number of file descriptors the library will open concurrently when flushing dirty pages from the cache.

The database environment's limit on open file descriptors to flush dirty pages 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_mp_max_openfd", one or more whitespace characters, and the number of open file descriptors. Because the DB_CONFIG file is read when the database environment is opened, it will silently overrule configuration done before that time.

The DbEnv::set_mp_max_openfd() method configures a database environment, not only operations performed using the specified DbEnv handle.

The `DbEnv::set_mp_max_openfd()` method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success.

### Parameters

#### maxopenfd

The maximum number of file descriptors that may be concurrently opened by the library when flushing dirty pages from the cache.

### Errors

The `DbEnv::set_mp_max_openfd()` method may fail and throw a DbException exception, encapsulating one of the following non-zero errors, or return one of the following non-zero errors:

#### EINVAL

An invalid flag value or parameter was specified.

### Class

DbEnv, DbMpoolFile

### See Also

Memory Pools and Related Methods

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