Make the group caches unlimited by default

The group caches should be large enough to hold entries for all internal
groups otherwise overall Gerrit performance may be poor. Make the group
caches unlimited by default and add a note to the documentation.

Change-Id: Ieef38b9dda71bf8c7174c1030e069037721f38c8
Signed-off-by: Edwin Kempin <ekempin@google.com>

Documentation/config-gerrit.txt

@@ -740,6 +740,9 @@ Default is 1024 for most caches, except:
 * `"diff"`: default is `10m` (10 MiB of memory)
 * `"diff_intraline"`: default is `10m` (10 MiB of memory)
 * `"diff_summary"`: default is `10m` (10 MiB of memory)
+* `"groups"`: default is unlimited
+* `"groups_byname"`: default is unlimited
+* `"groups_byuuid"`: default is unlimited
 * `"plugin_resources"`: default is 2m (2 MiB of memory)
 
 +
@@ -844,6 +847,11 @@ cache `"groups"`::
 Caches the basic group information of internal groups by group ID,
 including the group owner, name, and description.
 +
+For this cache it is important to configure a size that is larger than
+the number of internal Gerrit groups, otherwise general Gerrit
+performance may be poor. This is why by default this cache is
+unlimited.
++
 External group membership obtained from LDAP is cached under
 `"ldap_groups"`.
 
@@ -852,6 +860,11 @@ cache `"groups_byname"`::
 Caches the basic group information of internal groups by group name,
 including the group owner, name, and description.
 +
+For this cache it is important to configure a size that is larger than
+the number of internal Gerrit groups, otherwise general Gerrit
+performance may be poor. This is why by default this cache is
+unlimited.
++
 External group membership obtained from LDAP is cached under
 `"ldap_groups"`.
 
@@ -860,6 +873,11 @@ cache `"groups_byuuid"`::
 Caches the basic group information of internal groups by group UUID,
 including the group owner, name, and description.
 +
+For this cache it is important to configure a size that is larger than
+the number of internal Gerrit groups, otherwise general Gerrit
+performance may be poor. This is why by default this cache is
+unlimited.
++
 External group membership obtained from LDAP is cached under
 `"ldap_groups"`.
 

java/com/google/gerrit/server/account/GroupCacheImpl.java

@@ -52,12 +52,15 @@ public class GroupCacheImpl implements GroupCache {
       @Override
       protected void configure() {
         cache(BYID_NAME, AccountGroup.Id.class, new TypeLiteral<Optional<InternalGroup>>() {})
+            .maximumWeight(Long.MAX_VALUE)
             .loader(ByIdLoader.class);
 
         cache(BYNAME_NAME, String.class, new TypeLiteral<Optional<InternalGroup>>() {})
+            .maximumWeight(Long.MAX_VALUE)
             .loader(ByNameLoader.class);
 
         cache(BYUUID_NAME, String.class, new TypeLiteral<Optional<InternalGroup>>() {})
+            .maximumWeight(Long.MAX_VALUE)
             .loader(ByUUIDLoader.class);
 
         bind(GroupCacheImpl.class);