Defect HC-13495
Ingest proceeds even if Nifi is unable to communicate with HCL Cache
Software
| Customer case | Applies to | Corrected in |
|---|---|---|
| CS0272710 | V.9.1.6.0 | 9.1.9.0 |
Observed behavior
When there is a communication error with Redis, the WaitLink signal is not received and NiFi hangs.
Expected behavior
The communication links should be resilient and able to accommodate communication disruptions.
Resolution
NiFi uses Redis for WaitLinks. If Redis is down, the WaitLink signal is not received and NiFi hangs. A bug in the Redis client Redisson led to connections being silently closed. The Redisson version was updated to get the fix for this problem. A "watchdog" was also implemented to reconnect if the connection is lost. The logic was also updated so that local messages go directly to the local listeners without the need to go to Redis for notification.