Joe McDonnell has uploaded this change for review. ( 
http://gerrit.cloudera.org:8080/23944


Change subject: IMPALA-14724: Add support for using soft references in 
CatalogdMetaProvider
......................................................................

IMPALA-14724: Add support for using soft references in CatalogdMetaProvider

This adds the --local_catalog_cache_use_soft_references boolean
startup flag. If set to true (the default is false),
CatalogdMetaProvider configures the Guava Cache to use soft
references for values. Soft references can be garbage collected
when the system is under memory pressure. Effectively, the JVM
garbage collector can shrink the cache to keep the system running.
There are some conditions where this could make the system more
resilient:
 - A large query could come in and use excess memory for compilation
 - The cache itself could underestimate the memory usage of the
   metadata it is caching. That could lead it to oversubscribe the
   JVM memory. Allowing the cache memory to be garbage collected
   allows the system to adapt.
The downside is that non-cache JVM memory use can crowd out the cache
and cause more cache misses and traffic to catalogd.

Change-Id: I10efb6743d2f9e5b8cc47cdcc9c5893b005b9aa5
---
M be/src/runtime/exec-env.cc
M be/src/util/backend-gflag-util.cc
M common/thrift/BackendGflags.thrift
M fe/src/main/java/org/apache/impala/catalog/local/CatalogdMetaProvider.java
4 files changed, 22 insertions(+), 5 deletions(-)



  git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/44/23944/1
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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: I10efb6743d2f9e5b8cc47cdcc9c5893b005b9aa5
Gerrit-Change-Number: 23944
Gerrit-PatchSet: 1
Gerrit-Owner: Joe McDonnell <[email protected]>

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