nailgun doesn't work on some installations

With version 0.4.4, on some installations, we find that nailgun doesn’t seem to work - but on others it does. When it doesn’t work, the symptoms are similar to issue #4 - a zero length PNG file is served up. Sometimes, we also see an exception:

   throw err
   ^
Error: read ECONNRESET
   at exports._errnoException (util.js:1018:11)
   at TCP.onread (net.js:572:26)

Commenting out the call to plantuml.useNailgun(); solves the problem, but with the expected performance hit.

We can’t find any obvious pattern about which platforms (including versions) it works on - and which it doesn’t. E.g., we’ve seen it both work and not work on different Windows platforms, and likewise on Ubuntu platforms.

I realise this doesn’t give a lot to go on, but would it be possible to give me some pointers on debugging this issue further?

[markushedvall]

I’ve been working on an update to the node nailgun server with improved error handling that hopefully will be able to help finding the source of these kind of problems. I will integrate into node-plantuml in a near future.

[krisztianb]

@jcayzac many thanks for the reply and information.

For me the EOL has always been there so far. My module also supports binary output (PNG) and not just SVG. So a simple trim() won’t do. I’ll leave it as it is for the moment.

Regarding -pipeNoStderr you are right. Currently my module does not use this option. So errors are written to stderr and a “faulty” image containing a PlantUML error message is generated for the diagram. For some use cases I think this is not a bad solution. It might be worth adding an option for this though. I’ll think about it.

Regarding the newline termination: Yes, it can be seen in the example on the module’s README. But it sure can be a gotcha. The module is not going to do this for you. It can’t, because it doesn’t know when the input data ends. I think it is the job of the module’s consumer to take care about this.

Regarding PLANTUML_LIMIT_SIZE: You are right. We already ran into this problem when generating PNG output. I think it does not really make sense to use a pixel graphic format for diagrams, but it might be necessary for devices that can’t handle SVG. I’ll think about adding an option for this too and also maybe for the max. heap size that you are setting to 4 GB in your code.

Thanks again for your time and giving valuable feedback. It’s much appreciated. 👍