REW multiple instances on Linux

giacomus · Nov 26, 2024

Hello.
I think that multiple instances on Linux would be a great feature, given the necessity of analyzing and working with several measurements also for different configurations (e.g. sets of measurements for different speaker positioning).
Each instance may host tens of measurements so having multiple REW windows, distributed across different Linux virtual desktops would be an excellent option.

John Mulcahy · Nov 26, 2024

The REW installer only specifies single/multiple instances on Windows, otherwise it relies on the OS behaviour.

giacomus · Nov 26, 2024

John Mulcahy said:
The REW installer only specifies single/multiple instances on Windows, otherwise it relies on the OS behaviour.

Thanks John, and congratulations for Your great job with REW. It's simply amazing.
As a software developer, I know this is a programmer's choice. I understand the need of a unique instance when accessing the hardware, but for the pure analysis purpose I think multiple instances can be an option.

John Mulcahy · Nov 26, 2024

There's nothing in REW that enforces single instance. It's possible the installer shell script has some content that requests that, but that isn't behaviour the installation packager (install4j) exposes. The .sh file could be edited if there's some aspect you wish to change.

phofman · Nov 27, 2024

IMO there is nothing in the roomeqwizard shell script which checks for a running REW instance. However, the first REW instance checks and creates (if not found) a lock file & notify dir in /tmp

Code:

pavel@precision:~/REW$ strace -f /home/pavel/REW/jre/bin/java -Xms128m -Xmx3072m -Dsun.java2d.opengl=False -classpath /home/pavel/REW/.install4j/i4jruntime.jar:/home/pavel/REW/.install4j/launcherd9d2fef3.jar:/home/pavel/REW/./* install4j.roomeqwizard.RoomEQ_Wizard
....
[pid 1010640] openat(AT_FDCWD, "/tmp/i4j_at3lrPyykWVHrB8r-Nj_DNJMvpw=.lock", O_RDWR|O_CREAT, 0666) = 17
[pid 1010640] fstat(17, {st_mode=S_IFREG|0664, st_size=0, ...}) = 0
...
[pid 1010640] mkdir("/tmp/i4j_at3lrPyykWVHrB8r-Nj_DNJMvpw=.notify", 0777 <unfinished ...>

Indeed, these entries are created in /tmp:

Code:

pavel@precision:/tmp$ ls -l /tmp/i4j*
-rw-rw-r-- 1 pavel pavel    0 Nov 27 18:18 '/tmp/i4j_at3lrPyykWVHrB8r-Nj_DNJMvpw=.lock'

'/tmp/i4j_at3lrPyykWVHrB8r-Nj_DNJMvpw=.notify':
total 0

The next REW instance does check the lock file too (as confirmed with strace). If it finds them, it quits. If the /tmp/i4j_at3lrPyykWVHrB8r-Nj_DNJMvpw=.lock and /tmp/i4j_at3lrPyykWVHrB8r-Nj_DNJMvpw=.notify entries are manually deleted after the first instance starts up, a second instance starts up OK, creating the lock structures (with the very same name, that random-looking lock name is not random). Another manual delete -> another instance running.

So the hack/solution seems to be just adding rm -rf /tmp/i4j_* at the beginning of the launching roomeqwizard script.

IMO the install4j wrapper does make sure no other install4j->REW process gets started up.

John Mulcahy · Nov 27, 2024

That must be something the install4j launcher does. REW has it's own startup file, but it's only used to detect a failure to shut down normally.

phofman · Nov 27, 2024

Yes it most likely does the install4j wrapper as the lock names start with i4j. The install4j jar launches the REW startup class internally in java, the bash script roomeqwizard does not call any REW-specific jar.

phofman · Nov 27, 2024

The single-instance mode has an API in https://www.ej-technologies.com/resources/install4j/help/doc/api/launcher.html for receiving notifications from newly-started instances - that's what the created directory /tmp/i4j_xxx.notify likely does.

REW multiple instances on Linux

giacomus

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John Mulcahy

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giacomus

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John Mulcahy

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phofman

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John Mulcahy

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phofman

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