Hazelcast - Clustering and highly scalable data distribution platform for Java
logstash - logstash is a tool for managing events and logs.
Apache Storm - Apache Storm is a free and open source distributed realtime computation system.
rsyslog - Rsyslog is an enhanced syslogd supporting, among others, MySQL, PostgreSQL, failover log...
Redis - Redis is an open source in-memory data structure project implementing a distributed, in-memory key-value database with optional durability.
Graylog - Graylog is an open source log management platform for collecting, indexing, and analyzing both structured and unstructured data.