Berkeley DB

Shared Memory Regions

Each of the Berkeley DB subsystems within an environment is described by one or more regions. The regions contain all of the per-process and per-thread shared information, including mutexes, that comprise a Berkeley DB environment. These regions are created in one of three areas, depending on the flags specified to the DBENV→open function:

1. If the DB_PRIVATE flag is specified to DBENV→open, regions are created in per-process heap memory; that is, memory returned by malloc(3). In this case, the Berkeley DB environment may only be accessed by a single process, although that process may be multithreaded.

2. If the DB_SYSTEM_MEM flag is specified to DBENV→open, regions are created in system memory.When regions are created in system ...