[New Concept] Virtual Cache and Virtual MQ in the Trace analysis

[wu-sheng]

Virtual Cache

Virtual cache represents the cache nodes detected by server agents' plugins. The performance
metrics of the cache are also from the Cache client-side perspective.

For example, Redis plugins in the Java agent could detect the latency of command
As a result, SkyWalking would show traffic, latency, success rate, and sampled slow operations(write/read) powered by backend analysis capabilities in this dashboard.

The cache operation span should have

• It is an Exit or Local span
• Span's layer == CACHE
• Tag key = cache.type, value = The type of cache system , e.g. redis
• Tag key = cache.op, value = the operation of command , indicates the command is used for write or read operation
• Tag key = cache.command, value = the cache command , e.g. get,set,del
• Tag key = cache.key, value = the cache key
• If the cache system is in-memory (e.g. Guava-cache), agents' plugin would create a local span usually, and the span's peer would be null ,otherwise the peer is the network address(IP or domain) of Cache server.

Virtual Message Queue (MQ)

Virtual MQ represents the MQ nodes detected by server agents' plugins. The performance
metrics of the MQ are also from the MQ client-side perspective.

For example, Kafka plugins in the Java agent could detect the transmission latency of message
As a result, SkyWalking would show message count, transmission latency, success rate powered by backend analysis capabilities in this dashboard.

The MQ operation span should have

• It is an Exit(at producer side) or Entry(at consumer side) span
• Span's layer == MQ
• Tag key = mq.queue, value = MQ queue name
• Tag key = mq.topic, value = MQ queue topic , it's optional as some MQ don't have topic concept.
• Tag key = transmission.latency, value = Transmission latency from consumer to producer

[wu-sheng]

Official doc about the new dashboards

• Cache, https://skywalking.apache.org/docs/main/next/en/setup/service-agent/virtual-cache/
• MQ, https://skywalking.apache.org/docs/main/next/en/setup/service-agent/virtual-mq/