flprcache: Flush the process cache

Package: language

Usage

flprcache process

Parameters

process: Either the task number as printed by prcache, or the name of one of the tasks in the process. If no process is named, all processes are flushed from the cache (unless they are locked in the cache).

Description

When an executable task is first run, the CL spawns the associated executable file as a subprocess and then runs the task. When the task completes the process does not exit, rather it remains connected to the CL as a subprocess, but becomes idle waiting for another command from the CL. The set of such idle processes forms what is referred to as the CL "process cache". The purpose of the process cache is to minimize the overhead required to run a task; the first time a task is called response is slow since the process has to be executed, but thereafter response is fast provided the process remains in the cache.

The flprcache command flushes the process cache, terminating the connected subprocesses therein. If an argument is specified only the specific cache slot is cleared, otherwise all cache slots are flushed. Processes which have been "locked" in the cache with prcache are not flushed unless explicitly named.

Examples

1. Run prcache to get the process slot number, then flush the process by slot number.

cl> flpr 5

2. Flush all idle processes which are not locked in the cache.

cl> flpr

3. Flush the "x_system.e" process by naming the "directory" task, which is contained in that process. Lock a fresh copy of the process in the cache. This initializes the process, and may be necessary if a system task is interrupted at the wrong time.

cl> flpr dir; prc dir

Bugs

In some circumstances the CL may believe that a process in the process cache is running when this is not the case. The CL will not attempt to communicate with a running process, and will be unable to kill the process. If this happens the CL will hang up during logout and will have to be interrupted, causing a panic abort (this is harmless since the CL is then restarted). The user may eventually be required to kill the sub-process using operating system facilities.