I have a file server written in J6.02. It works most of the time - for
thousands of transactions - and then locks up. I have tracked it down
to a missing event. At the point of failure:
there is one socket, and that is the socket I am listening on. It is
marked asynchronous;
the socket shows up as readable in sdselect'' (indicating pending
connection);
if I issue socket_handler '' from the keybosrd the system will start
up again and run fine.
Apparently an FD_ACCEPT event has been lost.
At this point I will have to build a large load-generating setup to
create enough traffic to fail. I would prefer to troubleshoot this from
the source code, so I am asking for someone with access to the source
for 6.02 j.exe to send me the relevant modules for inspection, or to see
if they can find a problem in the area. (My understanding is that the
source for this bit is not open-source).
Below is the relevant part of my socket system. I'm including it just
to show that what I'm doing is simple and robust. The listening socket
is handled in the last 2 lines of socket_handler, which calls the recv
verb to do the accept. When the system is locked up, socklist has one
atom, as does sockobj (and they are correct - remember, a manual call to
socket_handler gets things moving again)
socket_handler =: 3 : 0
NB. Look for a writable socket with space
if. #wsocklist do.
'v r w e' =. sdselect_jsocket_ ($0);wsocklist;($0);0
done =. $0
for_l. sockobj {~ socklist i. w do. done =. done , 0 = send__l '' end.
wsocklist =: wsocklist -. done # w
end.
'v r w e' =. sdselect_jsocket_ socklist;($0);($0);0
for_l. sockobj {~ socklist i. r do. recv__l '' end.
)
recv =: 3 : 0
NB. sock is the socket number for the object
if. 0 = 0 {:: 'r c' =. sdaccept_jsocket_ sock do.
NB. this part configures the clone socket, not part of the problem
if. #callback do. cloneinfo =: cloneinfo callback~ c end.
o =. conew > {. cloneinfo
c create__o }. cloneinfo
end.
''
)
Henry Rich
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