Custom Query (1030 matches)

Under some circumstances apply is passing NIL as an optional parameter to an inlined function, instead of passing the default argument. (see attached paste from REPL)

(DEFPARAMETER *FILTERED-LIST* (REMOVE-IF-NOT (CONSTANTLY NIL) *LONG-LIST*))
took 75,108,000 microseconds (75.108000 seconds) to run.
     73,183,190 microseconds (73.183190 seconds, 97.44%) of which was spent in GC.
During that period, and with 8 available CPU cores,
     74,662,078 microseconds (74.662080 seconds) were spent in user mode
        171,601 microseconds ( 0.171601 seconds) were spent in system mode
 320,000,128 bytes of memory allocated.

(length *long-list*)
=> 20000000

(/ 320000128.0 (length *long-list*))
=> 16.000006
;; I.e. 16 bytes (64 bit cons) per element of original lisp

(asdf:implementation-identifier)
=> "ccl-1.8-f95-win-x64"

Probably the remove-if-not implementation could be enhanced.

The use case.

If the external process I started exceeds a timeout, I am trying to kill the process by sending it signal 9 using ccl:signal-external-process.

To know that the process exceeds the timeout, I pool it with ccl:external-process-status and check if the result is :running.

I.e. my code may approximately be represented as:

  (when (and (eq :running
                 (ccl:external-process-status lisp-process))
             (< end-time (get-universal-time)))
    (ccl:signal-external-process lisp-process 9))

But sometimes, the process finishes right after I got the :running from (ccl:external-process-status lisp-process), but before (ccl:signal-external-process lisp-process 9) tries to send it a signal.

In this case, CCL signals SIMPLE-ERROR with text "No such process".

I can not distinguish this error of process being finished, from other errors, because the CCL API doesn't specify particular condition type for this situation, and I can't rely on the text "No such process" as well (I believe the text is linux message for the corresponding errno value).

So, I try to setup a condition handler, and in the handler check the external-process-status again. If it is not :running, I deduce that the condition signaled is caused by the fact that the process has terminated (which is what my code wanted - to kill it, so I can just continue normal processing).

In most cases it works.

But sometimes, after the "No such process" error was signaled and the handler calls external-process-status, external-process-status returns :running. I assume this is because the external process is monitored by an internal CCL background thread, and the background thread hasn't yet synchronized the external-process CCL structure inspected by external-process-status.

As you see, it's not easy to reliable kill and external process by timeout. The API design forces user to deal with these race conditions.

I am not ready to propose a solution.

Maybe synchronization of the external-process object with the real situation before signaling the error would be a good idea?