parallel thread needs to wait for notification from FileSystemWatcher

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Quy
Quy 2023-8-29
评论： Quy 2023-8-29
I want ot run at least three threads in parallel. Thread 1 is the FileSystemWatcher, with the rest of the workers doing somethine else very specific, as determined by the action from the FileSystemWatcher.
How would I set this up so that threads 2 and 3 is just sitting and wait to get the spmdSend from thread 1. My code belows throw the error:
Error using testScript
Error detected on worker 2.
Caused by:
Error using testScript
A communication mismatch was encountered during spmdReceive. Worker 1 reached the end of the SPMD block without
completing the communication.ntered during spmdReceive. Worker 1 reached the end of the SPMD block without completing the communication.
spmd
if spmdIndex == 1
try
fswObj = System.IO.FileSystemWatcher('C:\Waves2');
fswObj.Filter = '*.*';
fswObj.NotifyFilter = System.IO.NotifyFilters.FileName;
fswObj.EnableRaisingEvents = true;
addlistener(fswObj,'Renamed',@notifyThread);
addlistener(fswObj,'Deleted',@notifyThread);
addlistener(fswObj,'Created',@notifyThread);
catch ME
fid = fopen('error.txt','w');
fprintf(fid,ME.message);
fprintf(fid,[num2str(ME.stack(1).line), ' : ', ME.stack(1).name, ' : ', ME.stack(1).file]);
fclose(fid);
end
elseif spmdIndex == 2
while true
[data, source] = spmdReceive(1);
disp(['Worker 2 received: ', data, ' from worker ', num2str(source)]);
end
else
while true
[data, source] = spmdReceive(1);
disp(['Worker 3 received: ', data, ' from worker ', num2str(source)]);
end
end
end
cleanup = onCleanup(@()myCleanupFun(fswObj));
function myCleanupFun(fswObj)
fswObj.EnableRaisingEvents = false;
end
function notifyThread(src,event)
filename = char(event.Name);
eventTypeFromNotify = char(event.ChangeType.ToString);
if strcmp(eventTypeFromNotify, 'Renamed')
spmdSend(['Sending to 2 for rename: ' filename],2)
end
if strcmp(eventTypeFromNotify, 'Deleted')
spmdSend(['Sending to 2 for delete: ' filename],2)
end
if strcmp(eventTypeFromNotify, 'Created')
spmdSend(['Sending to 3 for analysis: ' filename],3)
end
end
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Quy
Quy 2023-8-29
Thanks for the comment. I was able to get something to work, but the message displayed is delayed by one event of each core. Anyway around this?
function testScript()
spmd
if spmdIndex == 1
try
fswObj = System.IO.FileSystemWatcher('C:\Waves2');
fswObj.Filter = '*.*';
fswObj.NotifyFilter = System.IO.NotifyFilters.FileName;
fswObj.EnableRaisingEvents = true;
addlistener(fswObj,'Renamed',@notifyThread);
addlistener(fswObj,'Deleted',@notifyThread);
addlistener(fswObj,'Created',@notifyThread);
ii = 1;
while true
pause(.5); ii = ii+1;
if mod(ii,50) == 0
disp('loop')
end
end
catch ME
fid = fopen('error.txt','w');
fprintf(fid,ME.message);
fprintf(fid,[num2str(ME.stack(1).line), ' : ', ME.stack(1).name, ' : ', ME.stack(1).file]);
fclose(fid);
end
elseif spmdIndex == 2
while true
[data, source] = spmdReceive(1);
disp(['Worker 2 received: ', data, ' from worker ', num2str(source)]);
end
else
while true
[data, source] = spmdReceive(1);
disp(['Worker 3 received: ', data, ' from worker ', num2str(source)]);
end
end
end
end
function notifyThread(src,event)
filename = char(event.Name);
eventTypeFromNotify = char(event.ChangeType.ToString);
if strcmp(eventTypeFromNotify, 'Renamed')
spmdSend(['Rename: ' filename],2)
end
if strcmp(eventTypeFromNotify, 'Deleted')
spmdSend(['Delete: ' filename],2)
end
if strcmp(eventTypeFromNotify, 'Created')
spmdSend(['Analysis: ' filename],3)
end
end
Handy
Handy 2023-8-29
Ahh, I see that you put in the while loop in thread 1 as well to prevent it from completing. I did not think of that.

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采纳的回答

Quy
Quy 2023-8-29
I put in the while loop in the spmdIndex == 1 block of code to prevent the code running to completion. See my comment above.
  1 个评论
Quy
Quy 2023-8-29
But now I have a delay in the threads receiving the data. Please see this question for more info:
https://www.mathworks.com/matlabcentral/answers/2014591-delay-in-displaying-messages-in-parallel-threads-with-filesystemwatcher?s_tid=srchtitle

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