Guava Cache

The Guava instrumentation module, added in version 1.3.2, translates observability data provided by Guava Cache objects into prometheus metrics.

implementation 'io.prometheus:prometheus-metrics-instrumentation-guava:1.3.2'

<dependency>
    <groupId>io.prometheus</groupId>
    <artifactId>prometheus-metrics-instrumentation-guava</artifactId>
    <version>1.3.2</version>
</dependency>

In order to collect metrics:

• A single CacheMetricsCollector instance must be registered with the registry;
  • Multiple CacheMetricsCollector instances cannot be registered with the same registry;
• The Cache object must be instantiated with the recordStats() option, and then added to the CacheMetricsCollector instance with a unique name, which will be used as the value of the cache label on the exported metrics;
  • If the recordStats option is not set, most metrics will only return zero values;

var cache = CacheBuilder.newBuilder().recordStats().build();
var cacheMetrics = new CacheMetricsCollector();
PrometheusRegistry.defaultRegistry.register(cacheMetrics);
cacheMetrics.addCache("mycache", cache);

All example metrics on this page will use the mycache label value.

For all cache instances, the following metrics will be available:

# TYPE guava_cache_hit counter
# HELP guava_cache_hit Cache hit totals
guava_cache_hit_total{cache="mycache"} 10.0
# TYPE guava_cache_miss counter
# HELP guava_cache_miss Cache miss totals
guava_cache_miss_total{cache="mycache"} 3.0
# TYPE guava_cache_requests counter
# HELP guava_cache_requests Cache request totals
guava_cache_requests_total{cache="mycache"} 13.0
# TYPE guava_cache_eviction counter
# HELP guava_cache_eviction Cache eviction totals, doesn't include manually removed entries
guava_cache_eviction_total{cache="mycache"} 1.0
# TYPE guava_cache_size
# HELP guava_cache_size Cache size
guava_cache_size{cache="mycache"} 5.0

If the cache is an instance of LoadingCache, i.e. it is built with a loader function that is managed by the cache library, then metrics for observing load time and load failures become available:

# TYPE guava_cache_load_failure counter
# HELP guava_cache_load_failure Cache load failures
guava_cache_load_failure_total{cache="mycache"} 10.0
# TYPE guava_cache_loads counter
# HELP guava_cache_loads Cache loads: both success and failures
guava_cache_loads_total{cache="mycache"} 3.0
# TYPE guava_cache_load_duration_seconds summary
# HELP guava_cache_load_duration_seconds Cache load duration: both success and failures
guava_cache_load_duration_seconds_count{cache="mycache"} 7.0
guava_cache_load_duration_seconds_sum{cache="mycache"} 0.0034