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authorJoe Hunkeler <jhunkeler@gmail.com>2015-08-11 16:51:37 -0400
committerJoe Hunkeler <jhunkeler@gmail.com>2015-08-11 16:51:37 -0400
commit40e5a5811c6ffce9b0974e93cdd927cbcf60c157 (patch)
tree4464880c571602d54f6ae114729bf62a89518057 /pkg/language/doc/prcache.hlp
downloadiraf-osx-40e5a5811c6ffce9b0974e93cdd927cbcf60c157.tar.gz
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+.help prcache Feb86 language
+.ih
+NAME
+prcache -- cache a subprocess
+.ih
+USAGE
+prcache task [task ...]
+.ih
+PARAMETERS
+.ls task
+The name of a compiled IRAF task (not the filename of an executable file).
+.le
+.ih
+DESCRIPTION
+The CL maintains a small cache to store executable images. When the
+user invokes a task which calls an executable the cache is searched
+for the image before any attempt to load the executable image from
+disk. After completion of the task the CL retains the executable image
+in the process cache, until the space is needed by some other
+executable. Thus if a few commands are being executed frequently,
+the overhead of loading the image into core from disk is bypassed,
+which can result in a significant improvement in the response of the CL.
+
+By default, when the cache is full and a new executable must be run,
+the CL searches for the slot containing the task which has remained
+dormant the longest and replaces it with the new task.
+
+The \fIprcache\fR command gives the user some control over this process.
+Using it without any arguments shows the tasks which are currently
+stored in the process cache. For each slot one gets a line like the
+following.
+
+ [07] lyra!17763(4563X) H bin$x_images.e
+
+Here, 07 is the process slot number as required by \fIflprcache\fR to
+disconnect the process. The name "lyra" is the name of the node in the
+local network on which the process is executing; this is not normally
+the local node. In the example, 17763 (hex 4563X) is the process number
+(pid) of the executable. H indicates that the task is hibernating,
+i.e. the task was waiting in the cache to be invoked. R would show that
+the task was running. An L appended to either of these would show that the task
+had been locked into the cache by a previous prcache command.
+The last element on the line is the file name of the executable
+file which was loaded when the task was first invoked.
+
+If one or more task names are given as arguments, those tasks are locked
+into the cache, and will not be replaced by the CL without specific user
+intervention. If these tasks are not already in the cache, the
+corresponding executables are started, and the tasks are loaded into the cache.
+
+Note that the `process cache' described here, and the `parameter cache'
+described in the `cache' command are entirely distinct, and a given
+task may be found in either, both, or neither of the two caches.
+
+Also note that only executable images reside in the process cache.
+Thus, for example, if the \fInews\fR command is executed, it does not
+appear in the process cache, but the executable
+`system$x_system.e' does, because \fInews\fR calls \fIpage\fR,
+which is one of the many entries into the system executable.
+
+Locked process cache slots may only be freed with the \fIflprcache\fR command.
+.ih
+EXAMPLES
+1. Flush the system process and lock it back into the cache.
+
+.nf
+ cl> flpr dir
+ cl> prc dir
+.fi
+
+2. Print the current contents of the process cache.
+
+.nf
+ cl> prc
+ [10] lyra!17764(4564X) H bin$x_plot.e
+ [07] lyra!17763(4563X) H bin$x_images.e
+ [04] lyra!17455(442FX) HL bin$x_system.e
+ 0
+.fi
+
+3. Flush all processes which are not locked into the cache. This may be
+necessary after aborting a task to initialize (by re-executing) the
+associated process, which may not have recovered completely from the
+abort.
+
+ cl> flpr
+.ih
+BUGS
+The user is responsible for making sure that he does not lock all
+the slots in the cache.
+.ih
+SEE ALSO
+flprcache
+.endhelp