gtmsecshr commands
gtmsecshr commands
| Commands | Action | Comments |
|---|---|---|
WAKE_MESSAGE | Sends SIGALRM to specified process. | Used to inform receiving process that a resource (such as a critical section) it awaits has become available. |
CONTINUE_PROCESS | Sends SIGCONT to specified process. | Used to awake a process that has been suspended while holding a resource. [a] |
CHECK_PROCESS_ALIVE | Test sending a signal to specified process. [b] | Used to determine if a process owning a resource still exists; if not, the resource is available to be grabbed by another process that needs it. |
REMOVE_SEM | Remove a specified POSIX semaphore. | Used to remove an abandoned semaphore (for example, if the last attached process terminated abnormally). |
REMOVE_SHMMEM | Remove a specified shared memory segment. | Used to remove an abandoned shared memory segment. Before removing the segment, gtmsecshr checks that there are no processes attached to it. |
REMOVE_FILE | Remove a specified file. | Used to remove an abandoned socket file (for example, as a result of abnormal process termination) used for interprocess communication on platforms that do not support memory semaphores (msems); unused on other platforms. Before removal, gtmsecshr verifies that the file is a socket file, in directory $gtm_tmp, and its name matches GT.M socket file naming conventions. |
FLUSH_DB_IPCS_INFO | Writes file header of specified database file to disk. | The ipc resources (shared memory and semaphore) created for a database file are stored in the database file header. The first process opening a database file initializes these fields while the last process to use the database clears them. If neither of them has read-write access permissions to the database file, they set/reset these fields in shared memory and gtmsecshr will write the database file header from shared memory to disk on their behalf. |
[a] Please do not ever suspend a GT.M processes. In the event GT.M finds a process suspended while holding a resource, it is sent a SIGCONT. [b] This function is no longer needed and will be removed soon. |