V
Valeriy Bashkatov
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Hi, [quote user="mikaelstenmark"] Progress and UNIX Semaphores: Progress uses UNIX Semaphores to synchronize the activities of server processes and self-service client processes that are connected to a database. Semaphores are created and initialized by the Database broker when the database is started. UNIX semaphores are grouped into semaphore sets. Each semaphore set has a unique identifying number called a semid. Within a semaphore set, individual semaphores are identified by an integer that ranges from 0 to one less than the size of the semaphore set. The Database Broker creates a semaphore set when the database is started. The original recommended size of the semaphore set is the number of users (-n parameter) plus the number of servers (-Mn parameter) plus 4, however, the newer versions have added more auxiliary processes. The number of semaphores within a semaphore set (SEMMSL) is determined by the -n and -Mn startup parameter for each database. Progress auxiliary process need to be included in the Maximum Users (-n) count, i.e. APWs, AIW,BIW, WDOG, replication process, online backup, promon sessions, etc.. The amount of kernel memory required for semaphores is relatively small, so setting the limits higher than current needs probably won't affect performance. Semaphores are not used for single user sessions. Clients that connect to a remote database on a server machine do not use semaphores on the client machine. Recommended Semaphores Settings: SEMMNI : (Maximum number of semaphore identifiers) SEMMNI =Three semsets per active Enterprise database, otherwise one. The multiple semaphore sets feature is only available with the Enterprise Database Server product. When SEMMNI is exceeded errors such as “ Progress Error Semaphore limit exceeded (1131) ” arise. SEMMSL : (Maximum number of semaphores per set) SEMMSL = Maximum number of users on any database plus (+) the maximum number of remote servers for any database plus (+) 4 plus (+) the number auxiliary process. When SEMMSL is exceeded errors such as Warning: only wait semaphores are available. (1093) Less than minimum number of semaphores available (1130) SEMMNS : (Maximum number of semaphores system-wide) SEMMNS = SEMMSL multiply by (*) the number of active databases. When SEMMNS is exceeded the following errors arise: Warning: only wait semaphores are available. (1093) Semaphore limit exceeded (1131) No available wait semaphore. (1195) SEMMNU : SEMMNU = SEMMNS When SEMMNS is exceeded the following errors arise: Too many users requested semaphore undo, increase SEMMNU. (1081) MAXUMEM : Maximum amount of memory that will be used to run a process Typically needs increasing when SHMMAX, SHMSEG are raised. [/quote] knowledgebase.progress.com/.../P61278
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