ExecDos hanging on Java process

kalverson · 6th March 2015, 11:42

This is just to document that it happened. I resolved my issue by using the older nsExec in place of ExecDos. I lose the output in the log, but it does not hang. Something about the Java output from flyway.cmd version 3.1 is causing ExecDos to hang up. When the same process is run in a command shell it runs fine. JStack on the hanging process just shows Java is outputting; there doesn't seem to be anything suspicious.

kalverson · 31st March 2015, 17:44

The 4k pipe is probably filling up. From a Google link on why Java processes hang:

Java doesn't do anything in this area. It just uses OS services to create the pipes. All Unix like OSs and Windows behave the same in this regard: A pipe with a 4K is created between parent and child. When that pipe is full (because one side isn't reading), the writing process blocks. This is the standard since the inception of pipes. There is not much Java can do.

aerDNA · 31st March 2015, 18:07

Quote:

I resolved my issue by using the older nsExec in place of ExecDos. I lose the output in the log, but it does not hang.

What about nsExec::ExecToLog ?

kalverson · 9th December 2016, 14:30

I haven't tried the logging part yet. I did run into this same issue again with a different product running a postgresql sql script. Once again the install hangs on ExecDos.

6th March 2015, 11:42	#1
kalverson Senior Member Join Date: May 2007 Location: Maple Grove, Minnesota Posts: 134	ExecDos hanging on Java process This is just to document that it happened. I resolved my issue by using the older nsExec in place of ExecDos. I lose the output in the log, but it does not hang. Something about the Java output from flyway.cmd version 3.1 is causing ExecDos to hang up. When the same process is run in a command shell it runs fine. JStack on the hanging process just shows Java is outputting; there doesn't seem to be anything suspicious.

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31st March 2015, 17:44	#2
kalverson Senior Member Join Date: May 2007 Location: Maple Grove, Minnesota Posts: 134	The 4k pipe is probably filling up. From a Google link on why Java processes hang: Java doesn't do anything in this area. It just uses OS services to create the pipes. All Unix like OSs and Windows behave the same in this regard: A pipe with a 4K is created between parent and child. When that pipe is full (because one side isn't reading), the writing process blocks. This is the standard since the inception of pipes. There is not much Java can do.

9th December 2016, 14:30	#4
kalverson Senior Member Join Date: May 2007 Location: Maple Grove, Minnesota Posts: 134	I haven't tried the logging part yet. I did run into this same issue again with a different product running a postgresql sql script. Once again the install hangs on ExecDos.