Under concurrent load, child process exit event fires before IO is complete, causing errors fix with tests #2 #3
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Under heavy load (in the context of web application, for example using nestjs) some of the requests fail: 1. According to child process documentation (https://nodejs.org/docs/latest-v14.x/api/child_process.html#child_process_event_exit), exit even can fire before stdio is closed. In such cases respond() is being called with code 0 (success), no error and no data. This results in an error in the calling code, because filename is expected but is not returned. I added additional error checking to respond() to handle this case. 2. Given the above, it's probably not a good idea to subscribe to exit event at all. I commented out the on('exit'..) code. on('close') should be sufficient. Tested it under some load (30 concurrent connections for 2 minutes) - no errors, 5000+ PDFs rendered.
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marcbachmann#644
and
kvasserman#1