Default HCL Cache configuration
The HCL Cache default configuration file (cache_cfg.yaml) contains all provided (out-of-the-box) cache configurations.
To make changes to any defaults that are set in this file, modify the respective properties within the custom HCL Cache configuration file. Settings in the custom configuration file, which shares the same format as the default configuration file, override settings in the default configuration file.
| Configuration | Description | ||
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| clientId | This value is used to identify the originating container. The clientId is
stored along with cache entries and used with invalidation messages. On a Kubernetes environment,
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| namespace | An optional namespace. If configured, the namespace is pre-appended to all the cache names in
the Redis server. This is done to allow multiple environments to share
the same Redis database. This parameter is configured by default to match the tenant, environment and environment type. |
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| logMetricsFrequency | The frequency in seconds at which cache metrics are written to the logs. The default value is
900 (15 minutes). The logger can be disabled
by:
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| redis | |||
| enabled | Whether Redis is enabled. By default this value is set to false. Use the value true in the custom HCL Cache configuration file to enable remote caching. |
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| yamlConfig |
Path to the YAML configuration file for the Redis connection. By default this value is set to /SETUP/hcl-cache/redis_cfg.yaml. |
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| circuitBreaker |
For caches that enable both local and remote interfaces, the circuit breaker configuration allows the cache to work independently in local mode during a Redis outage. A cache is set in outage mode when conditions for both minimumFailureTimeMs and minimumConsecutiveFailures are met. During this time, connections to Redis are retried only after the time interval that is set by retryWaitTimeMs has elapsed. When retryWaitTimeMs is reached, the circuit breaker allows connection attempts to the Redis server to resume. A successful request restores the connection from outage mode. If the number of failures continues, and reaches the value set in minimumConsecutiveFailuresResumeOutage, the client is once again set in outage mode, and must again reach the retryWaitTimeMs value before the re-establishment of a connection is attempted. The minimumConsecutiveFailuresResumeOutage setting is used to allow for quick testing of the connection after an outage without having to wait for minimumFailureTimeMs and minimumConsecutiveFailures values to be reached again. See also maxTimeToLiveWithRemoteOutage. |
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| circuitBreaker configurations | retryWaitTimeMs | Once a cache is set in outage mode, retryWaitTimeMs is the time, in
milliseconds, that must elapse before the Redis connection is retried. By default this value is set to 30000 (30 seconds). |
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| minimumFailureTimeMs | The time, in milliseconds, that must elapse before a cache can be put into outage mode. This
amount of time, and minimumConsecutiveFailures must be satisfied before the
circuit breaker closes the Redis connection. By default this value is set to 10000 (10 seconds). |
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| minimumConsecutiveFailures |
The minimum number of consecutive connection attempt failures before a cache can be set in outage mode. This value, and minimumFailureTimeMs must be satisfied before the circuit breaker closes the Redis connection. By default this value is set to 20 connection attempts. |
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| minimumConsecutiveFailuresResumeOutage |
The minimum number of consecutive connection attempt failures before a cache can be set back into outage mode. When a connection is in outage mode and reaches the retryWaitTimeMs value, the circuit breaker will allow connection attempts to the Redis server. In order to allow for quick testing of the connection without an undue excess of connection attempts, the minimumConsecutiveFailuresResumeOutage is used. If minimumConsecutiveFailuresResumeOutage is reached, the connection is placed back into outage mode, without having to wait for the entire minimumFailureTimeMs and minimumConsecutiveFailures condition cycle to be satisfied once again. By default this value is set to 2 connection attempts. |
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| cacheConfigs | |||
| cacheName | The name of the cache to configure. The size and size in megabytes parameters are obtained from the DynaCache configuration in Open Liberty Server. The cache name defaultCacheConfig is reserved and specifies the defaults for all caches. | ||
| localCache | |||
| localCache configurations | enabled | Enables this cache to make use of local caching. | |
| maxInactivityWithRemote | The time, in seconds, this cache can remain
inactive in its local state. When remote caching is enabled, this setting enforces a maximum inactivity time allowed for this cache before being invalidated. This optional configuration is used to have shorter timeouts when the local cache is acting as a replica/near cache of the remote cache. By default this value is set to 0 (disabled). |
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| maxTimeToLiveWithRemote | The time, in seconds, that this cache can remain valid. When remote caching is enabled, this setting enforces a maximum timeout allowed for this cache. This optional configuration can be used to specify shorter timeouts when the local cache is acting as a near cache for the remote cache. By default this value is set to 0 (disabled). |
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| maxTimeToLiveWithRemoteOutage | The time, in seconds, this cache can remain valid during a remote outage. When the circuit breaker is enabled, and a cache is in outage mode, this setting is used to enforce a new timeout on the local cache. A short timeout is used as invalidations are not available if Redis is not operational. By default this value is set to 300 seconds. |
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| remoteCache | |||
| remoteCache configurations | enabled | Enables this cache to rely on the use of remote caching. By default this is set to enabled when a Redis connection is configured. |
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| defaultTimeout | Normally cache entries specify a maximum time to live (timeout) in seconds when they are
created. But if no timeout is specified by the cache entry, then the
defaultTimeout setting is used for that cache
entry. By default, the defaultTimeout parameter value is set to 172800 seconds (2 days). Important: Redis must be configured with a
volatile-* less-recently-used (LRU) setting. For more information,
see Using Redis as an LRU cache in the Redis
documentation. |
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| maximumTimeout | Normally cache entries specify a maximum time to live (timeout) in
seconds when they are created. But if no timeout is specified by the
cache entry, then the defaultTimeout setting is
used for that cache entry. If the defaultTimeout is set to a value that is higher than the maximumTimeout, then the maximumTimeout value is used. By default, the maximumTimeout parameter value is set to 604800 seconds (7 days). |
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| Codec options (compression) | The codec configuration element under
remoteCache can be used to modify the default
binary codec that Redis uses to serialise cache entry values. The HCL
Cache will utilise the LZ4 compression method for
compressing. |
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| Cache Directives | The cache name element may be used to activate cache directives. They
are only enabled for baseCache by
default.Although the HCL Cache allows for local and/or remote caching at the cache level, it is sometimes preferable to select which caches are used at the cache entry level. Cache entries for search operations may grow unbounded and have limited reusability (hit ratios). While local level caching can be beneficial, distant caching can be costly since it adds I/O overhead, consumes a large amount of Redis memory, and necessitates frequent Redis memory maintenance operations. When a cache's directives are enabled, the cachespec.xml can contain the following attributes to govern whether local or remote caching is utilised at the cache entry level:
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