Interlisp
Why is CLOSEALL no longer supported?
It bombs out if MULTIPLE-STREAMS-PER-FILE-ALLOWED is true.
What's wrong with closing all the streams, even if some files have been opened with multiple streams? Close them all.
oh, maybe people didn't realize how unsafe it was?
for example Issue #319
Use (MAPC (OPENP) #'CLOSEF?)
CLOSEALL won't do it if the stream has the CLOSEALL property (probably should be DONTCLOSEALL).
But it seems that this has nothing to do with whether there are multiple streams per file. It is perhaps unsafe for certain streams to be closed. The MAPC, which is what I do, has the same danger (more so, since it doesn't test a streamprop)
CLOSEALL is up there with HARDRESET and is possibly more dangerous -- it closes all the streams of all the processes. Issue #319 comes up as something that can happen -- when you restart after a SaveVM or Sysout or Logout and you had a dribble file open, you get a stack overflow from trying to print the warning that a file was closed, but printing the warning to a closed file causes another error which tries to ... etc.
Allowing multiple streams per file was an attempt to solve a problem of making lisp thread-safe to a degree (without PREEMPTIVE scheduling) so each process could use files without worrying that some other process would open the same file and move around the file pointer (or close the file).
There may be streams that are dangerous to close, and some of those may not even be registered in the list of open files that the various devices maintain (which is what CLOSEALL should look at, not the \OPENFILES variable). But the dangerous ones should be marked as not-closeall-able when they are created. Probably just the special streams that are set up in CLSTREAMS, and the dribble stream. I
On Aug 6, 2022, at 10:17 AM, Larry Masinter @.***> wrote:
CLOSEALL is up there with HARDRESET and is possibly more dangerous -- it closes all the streams of all the processes. Issue #319 https://github.com/Interlisp/medley/issues/319 comes up as something that can happen -- when you restart after a SaveVM or Sysout or Logout and you had a dribble file open, you get a stack overflow from trying to print the warning that a file was closed, but printing the warning to a closed file causes another error which tries to ... etc.
Allowing multiple streams per file was an attempt to solve a problem of making lisp thread-safe to a degree (without PREEMPTIVE scheduling) so each process could use files without worrying that some other process would open the same file and move around the file pointer (or close the file).
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In fact, it would be better and a little bit safer if closeall also takes a host argument (CLOSEALL 'DSK), in addition to whatever filters there might be
You asked why things were the way they were, and I was trying to answer the question. man CLOSEALL doesn't give any hints -- maybe in some release note?