druid.segmentCache.locationSelectorStrategy config raise Exception

[meicool]

Affected Version
0.18.1

Description
When add local cache ,we use druid.segmentCache.locationSelectorStrategy config to scan the disk,but it raise some exception like:

Problem parsing object at prefix[druid.segmentCache]: Cannot construct instance of org.apache.druid.segment.loading.LeastBytesUsedStorageLocationSelectorStrategy (no Creators, like default construct, exist): no String-argument constructor/factory method to deserialize from String value ('roundRobin')
2 historical node ,1 master node
My configure: druid.segmentCache.locationSelectorStrategy=mostAvailableSize
the exception log :
Problem parsing object at prefix[druid.segmentCache]: Cannot construct instance of org.apache.druid.segment.loading.MostAvailableSizeStorageLocatio nSelectorStrategy (no Creators, like default construct, exist): no String-argument constructor/factory method to deserialize from String value ('mostAvailableSize')
at [Source: UNKNOWN; line: -1, column: -1] (through reference chain: org.apache.druid.segment.loading.SegmentLoaderConfig["locationSelectorStrategy
"]).
at org.apache.druid.guice.JsonConfigProvider.bind(JsonConfigProvider.java:151) (via modules: com.google.inject.util.Modules$OverrideModule -> com.
google.inject.util.Modules$OverrideModule -> org.apache.druid.guice.StorageNodeModule)
at org.apache.druid.guice.JsonConfigProvider.bind(JsonConfigProvider.java:151) (via modules: com.google.inject.util.Modules$OverrideModule -> com.
google.inject.util.Modules$OverrideModule -> org.apache.druid.guice.StorageNodeModule)
while locating com.google.common.base.Supplier<org.apache.druid.segment.loading.SegmentLoaderConfig>
at org.apache.druid.guice.JsonConfigProvider.bind(JsonConfigProvider.java:152) (via modules: com.google.inject.util.Modules$OverrideModule -> com.
google.inject.util.Modules$OverrideModule -> org.apache.druid.guice.StorageNodeModule)
while locating org.apache.druid.segment.loading.SegmentLoaderConfig
for the 2nd parameter of org.apache.druid.segment.loading.SegmentLoaderLocalCacheManager.(SegmentLoaderLocalCacheManager.java:88)
while locating org.apache.druid.segment.loading.SegmentLoaderLocalCacheManager
at org.apache.druid.guice.LocalDataStorageDruidModule.configure(LocalDataStorageDruidModule.java:51) (via modules: com.google.inject.util.Modules$
OverrideModule -> com.google.inject.util.Modules$OverrideModule -> org.apache.druid.guice.LocalDataStorageDruidModule)
while locating org.apache.druid.segment.loading.SegmentLoader
for the 1st parameter of org.apache.druid.server.SegmentManager.(SegmentManager.java:100)
at org.apache.druid.cli.CliHistorical.lambda$getModules$0(CliHistorical.java:90) (via modules: com.google.inject.util.Modules$OverrideModule -> co
m.google.inject.util.Modules$OverrideModule -> org.apache.druid.cli.CliHistorical$$Lambda$13/701487403)
while locating org.apache.druid.server.SegmentManager
for the 8th parameter of org.apache.druid.server.coordination.ServerManager.(ServerManager.java:101)
at org.apache.druid.cli.CliHistorical.lambda$getModules$0(CliHistorical.java:89) (via modules: com.google.inject.util.Modules$OverrideModule -> co
m.google.inject.util.Modules$OverrideModule -> org.apache.druid.cli.CliHistorical$$Lambda$13/701487403)
while locating org.apache.druid.server.coordination.ServerManager
at org.apache.druid.cli.CliHistorical.lambda$getModules$0(CliHistorical.java:92) (via modules: com.google.inject.util.Modules$OverrideModule -> co
m.google.inject.util.Modules$OverrideModule -> org.apache.druid.cli.CliHistorical$$Lambda$13/701487403)
while locating org.apache.druid.query.QuerySegmentWalker
for the 2nd parameter of org.apache.druid.server.QueryLifecycleFactory.(QueryLifecycleFactory.java:52)
at org.apache.druid.server.QueryLifecycleFactory.class(QueryLifecycleFactory.java:52)
while locating org.apache.druid.server.QueryLifecycleFactory
for the 1st parameter of org.apache.druid.server.QueryResource.(QueryResource.java:121)
at org.apache.druid.server.QueryResource.class(QueryResource.java:79)
while locating org.apache.druid.server.QueryResource

[FrankChen021]

According to the code, the configuration item should be druid.segmentCache.locationSelectorStrategy.type instead of druid.segmentCache.locationSelectorStrategy.

But even using the right property name corresponding to the code, customer strategy still does not work because of a failure of StorageLocation injection.

Since locationSelectorStrategy is introduced by #8038, @sashidhar would you take a look at this problem ?

[meicool]

Thank you for your help,I replaced the configuration item with druid.segmentCache.locationSelectorStrategy.type,but the same error persisted

[FrankChen021]

@meicool yes,as I mentioned above, it still doesn't work. I think some code fix is needed.

[jihoonson]

@meicool @FrankChen021 thank you for looking at this issue. It seems like StorageLocationSelectorStrategy is not JSON-serde-able even though it should be. Probably it can be fixed by annotating the constructor and its variable properly in all its implementations.

[FrankChen021]

@jihoonson Hi, a PR has been submitted to fix this problem. Please check the PR at your convenience.