This module provides a REST API to help converting existing cache from H2 to chronicle-map, which requires the
Administrate Caches or
Administrate Server capabilities to be executed.
The migration must be executed before switching to use chronicle-map, while Gerrit cache is still backed by H2.
The migration can be run online without any disruption of the Gerrit server. However note that since the migration perform many, sequential reads from the H2 database, it will participate to the overall database load, so you should test accordingly.
The migration would do the following:
NOTE: The existing cache parameters are kept in
gerrit.configonly when they are all defined (avgKeySize, avgValueSize, maxEntries and maxBloatFactor), otherwise the migration process will recalculate them and create the new cache based on the new values.
The following caches will be migrated (if they exist and contain any data):
The migration should be performed as follows:
cache-chroniclemap.jarfile in the
INFO com.google.gerrit.server.plugins.PluginLoader : Loaded plugin cache-chroniclemap
curl -v -XPUT -u <admin> '<gerrit>/a/plugins/cache-chroniclemap/migrate?[size-multiplier=FACTOR]&[bax-bloat-factor=MULTIPLIER]'
This might require some time, depending on the size of the H2 caches and it will terminate with the output of the configuration that should be places in
etc/gerrit.configin order to leverage the newly created caches correctly.
[cache "diff"] maxEntries = 216 avgKeySize = 188 avgValueSize = 796 maxBloatFactor = 1 [cache "persisted_projects"] maxEntries = 3 avgKeySize = 80 avgValueSize = 4087 maxBloatFactor = 1 [cache "diff_summary"] maxEntries = 216 avgKeySize = 192 avgValueSize = 254 maxBloatFactor = 1 [cache "accounts"] maxEntries = 2 avgKeySize = 52 avgValueSize = 194 maxBloatFactor = 1 [cache "mergeability"] maxEntries = 2444 avgKeySize = 150 avgValueSize = 20 maxBloatFactor = 1 [cache "web_sessions"] maxEntries = 94852 avgKeySize = 68 avgValueSize = 382 maxBloatFactor = 1
Optionally the REST endpoint can receive the following additional arguments:
maximum number of times chronicle-map cache is allowed to grow in size. default:3