We are connecting to janusgraph using java. A cluster connection with the gremlin driver is used for the connectivity. At the start, we were getting out of memory error, but tweaking some changes in gremlin-server.yaml resolved the issue.
The issue raised on StackOverflow: 

Changes made in gremlin-server.yaml:
writeBufferLowWaterMark: 9500000
writeBufferHighWaterMark: 10000000
Every query gets stuck at 119 MB for some time i.e approx 5 mins and again starts working.

Attaching a screenshot of the error.

Gremlin server configurations:

maxInitialLineLength: 4096
maxHeaderSize: 8192
maxChunkSize: 16384
maxContentLength: 2000000000
maxAccumulationBufferComponents: 1024
resultIterationBatchSize: 128
writeBufferLowWaterMark: 9500000
writeBufferHighWaterMark: 10000000
threadPoolWorker: 30
gremlinPool: 0

How can the issue be solved ??

Thanks & Regards,

Vinayak