Adaguc throws HTTP 500 when Redis connection drops

[mgrunbauer]

When running adaguc-server using Redis, requests can fail with a HTTP 500 response when Redis is not responding. The adaguc-server logging shows that the Redis server was not available:

redis.exceptions.ConnectionError: Error while reading from <adaguc-redis-hostname>: (104, 'Connection reset by peer')

The requests directly before this call (milliseconds earlier) worked fine. After waiting 5-10 minutes, the same HTTP request worked again.

Other details I found:

• Happened with requests to both EDR's instance and cube.
• Happened in versions 2.26.0, 2.23.0 and 2.21.0.
• Occurred 119 times in the past 2 months.
• Sometimes does not happen for 7-10 days, sometimes happens about 30 times in a day.