Purges Server, MasterServices, and RegionServerServices from
CoprocessorEnvironments. Replaces removed functionality with
a set of carefully curated methods on the *CoprocessorEnvironment
implementations (Varies by CoprocessorEnvironment in that the
MasterCoprocessorEnvironment has Master-type facility exposed,
and so on).
A few core Coprocessors that should long ago have been converted
to be integral, violate their context; e.g. a RegionCoprocessor
wants free access to a hosting RegionServer (which may or may not
be present). Rather than let these violators make us corrupte the
CP API, instead, we've made up a hacky system that allows core
Coprocessors access to internals. A new CoreCoprocessor Annotation
has been introduced. When loading Coprocessors, if the instance is
annotated CoreCoprocessor, we pass it an Environment that has been
padded w/ extra-stuff. On invocation, CoreCoprocessors know how to
route their way to these extras in their environment.
See the *CoprocessoHost for how the do the check for CoreCoprocessor
and pass a fatter *Coprocessor, one that allows getting of either
a RegionServerService or MasterService out of the environment
via Marker Interfaces.
Removed org.apache.hadoop.hbase.regionserver.CoprocessorRegionServerServices
M hbase-endpoint/src/main/java/org/apache/hadoop/hbase/security/access/SecureBulkLoadEndpoint.java
This Endpoint has been deprecated because its functionality has been
moved to core. Marking it a CoreCoprocessor in the meantime to
minimize change.
M hbase-rsgroup/src/main/java/org/apache/hadoop/hbase/rsgroup/RSGroupAdminEndpoint.java
This should be integral to hbase. Meantime, marking it CoreCoprocessor.
M hbase-server/src/main/java/org/apache/hadoop/hbase/Server.java
Added doc on where it is used and added back a few methods we'd
removed.
A hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/CoreCoprocessor.java
New annotation for core hbase coprocessors. They get richer environment
on coprocessor loading.
A hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/HasMasterServices.java
A hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/HasRegionServerServices.java
Marker Interface to access extras if present.
M hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/MasterCoprocessorEnvironment.java
Purge MasterServices access. Allow CPs a Connection.
M hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/RegionCoprocessorEnvironment.java
Purge RegionServerServices access. Allow CPs a Connection.
M hbase-server/src/main/java/org/apache/hadoop/hbase/coprocessor/RegionServerCoprocessorEnvironment.java
Purge MasterServices access. Allow CPs a Connection.
M hbase-server/src/main/java/org/apache/hadoop/hbase/quotas/MasterSpaceQuotaObserver.java
M hbase-server/src/main/java/org/apache/hadoop/hbase/quotas/QuotaCache.java
We no longer have access to MasterServices. Don't need it actually.
Use short-circuiting Admin instead.
D hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/CoprocessorRegionServerServices.java
Removed. Not needed now we do CP Env differently.
M hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java
No need to go via RSS to getOnlineTables; just use HRS.
And so on. Adds tests to ensure we can only get at extra info
if the CP has been properly marked.
- Table moving to RSG was buggy, because it left the table unassigned.
Now it is fixed we immediately assign to an appropriate RS
(MoveRegionProcedure).
- Table was locked while moving, but unassign operation hung, because
locked table queues are not scheduled while locked. Fixed.
- ProcedureSyncWait was buggy, because it searched the procId in
executor, but executor does not store the return values of internal
operations (they are stored, but immediately removed by the cleaner).
- list_rsgroups in the shell show also the assigned tables and servers.
Signed-off-by: Michael Stack <stack@apache.org>
* batch validation and preparation is done before we start iterating over operations for writes
* durability, familyCellMaps and observedExceptions are batch wide and are now sotred in BatchOperation,
as a result durability is consistent across all operations in a batch
* for all operations done by preBatchMutate() CP hook, operation status is updated to success
* doWALAppend() is modified to habdle replay and is used from doMiniBatchMutate()
* minor improvements
Signed-off-by: Michael Stack <stack@apache.org>
The archived Procedure WALs are moved to <hbase_root>/oldWALs/masterProcedureWALs
directory. TimeToLiveProcedureWALCleaner class was added which
regularly cleans the Procedure WAL files from there.
The TimeToLiveProcedureWALCleaner is now added to
hbase.master.logcleaner.plugins to clean the 2 WALs in one run.
A new config parameter is added hbase.master.procedurewalcleaner.ttl
which specifies how long a Procedure WAL should stay in the
archive directory.
Signed-off-by: Michael Stack <stack@apache.org>
This reverts commit 0d0c330401.
Backing out filterlist regression, see HBASE-18957. Work continuing branch for HBASE-18410.
Signed-off-by: Peter Somogyi <psomogyi@cloudera.com>
Signed-off-by: Michael Stack <stack@apache.org>
This reverts commit 743f3ae221.
Backing out filterlist regression, see HBASE-18957. Work continuing branch for HBASE-18410.
Signed-off-by: Peter Somogyi <psomogyi@cloudera.com>
Signed-off-by: Michael Stack <stack@apache.org>
This reverts commit 7c2622baf7.
Backing out filterlist regression, see HBASE-18957. Work continuing branch for HBASE-18410.
Signed-off-by: Peter Somogyi <psomogyi@cloudera.com>
Signed-off-by: Michael Stack <stack@apache.org>
Patch ArrayIndexOutOfBoundsException when current() is called after
advance() has already returned false
Signed-off-by: Chia-Ping Tsai <chia7712@gmail.com>
These functions have been changed to return Optional<T> instead of T, where T = old return type.
- ObserverContext#getCaller
- RpcCallContext#getRequestUser
- RpcCallContext#getRequestUserName
- RpcServer#getCurrentCall
- RpcServer#getRequestUser
- RpcServer#getRequestUserName
- RpcServer#getRemoteAddress
- ServerCall#getRequestUser
Change-Id: Ib7b4e6be637283755f55755dd4c5124729f7052e
Signed-off-by: Apekshit Sharma <appy@apache.org>
CompactionRequest was removed from CP in HBASE-18453, this change reintroduces
CompatcionRequest to CP as a read-only interface called CompactionRequest.
The CompactionRequest class is renamed to CompactionRequestImpl.
Additionally, this change removes selectionTimeInNanos from CompactionRequest and
uses selectionTime as a replacement. This means that CompactionRequest:toString
is modified and compare as well.
Signed-off-by: Michael Stack <stack@apache.org>
- Change Service Coprocessor#getService() to List<Service> Coprocessor#getServices()
- Checkin the finalized design doc into repo
- Added example to javadoc of Coprocessor base interface on how to implement one in the new design
------------------------------------------------------
TL;DR
------------------------------------------------------
We are moving from Inheritence
- Observer *is* Coprocessor
- FooService *is* CoprocessorService
To Composition
- Coprocessor *has* Observer
- Coprocessor *has* Service
------------------------------------------------------
Design Changes
------------------------------------------------------
- Adds four new interfaces - MasterCoprocessor, RegionCoprocessor, RegionServierCoprocessor,
WALCoprocessor
- These new *Coprocessor interfaces have a get*Observer() function for each observer type
supported by them.
- Added Coprocessor#getService() to base interface. All extending *Coprocessor interfaces will
get it from the base interface.
- Added BulkLoadObserver hooks to RegionCoprocessorHost instad of SecureBulkLoadManager doing its
own trickery.
- CoprocessorHost#find*() fuctions: Too many testing hooks digging into CP internals.
Deleted if can, else marked @VisibleForTesting.
------------------------------------------------------
Backward Compatibility
------------------------------------------------------
- Old coprocessors implementing *Observer won't get loaded (no backward compatibility guarantees).
- Third party coprocessors only implementing Coprocessor will not get loaded (just like Observers).
- Old coprocessors implementing CoprocessorService (for master/region host)
/SingletonCoprocessorService (for RegionServer host) will continue to work with 2.0.
- Added test to ensure backward compatibility of CoprocessorService/SingletonCoprocessorService
- Note that if a coprocessor implements both observer and service in same class, its service
component will continue to work but it's observer component won't work.
------------------------------------------------------
Notes
------------------------------------------------------
Did a side-by-side comparison of CPs in master and after patch. These coprocessors which were just
CoprocessorService earlier, needed a home in some coprocessor in new design. For most it was clear
since they were using a particular type of environment. Some were tricky.
- JMXListener - MasterCoprocessor and RSCoprocessor (because jmx listener makes sense for
processes?)
- RSGroupAdminEndpoint --> MasterCP
- VisibilityController -> MasterCP and RegionCP
These were converted to RegionCoprocessor because they were using RegionCoprocessorEnvironment
which can only come from a RegionCPHost.
- AggregateImplementation
- BaseRowProcessorEndpoint
- BulkDeleteEndpoint
- Export
- RefreshHFilesEndpoint
- RowCountEndpoint
- MultiRowMutationEndpoint
- SecureBulkLoadEndpoint
- TokenProvider
Change-Id: I813145f2bc11815f52ac703563b879962c249764
Adjust exception control flow to fix findbugs warning
NP_NULL_ON_SOME_PATH_EXCEPTION, Possible null pointer dereference of
regionSink in org.apache.hadoop.hbase.tool.Canary$RegionMonitor.run()
on exception path
Added assertion checks to make sure that the error code for the
ToolRunner run() method is used.
Testing Done: Checked that TestCanaryTool unit tests fail when there is
an error code in the current Canary run.
Signed-off-by: Andrew Purtell <apurtell@apache.org>
Changed the type hierarchy of Canary sinks to reduce confusion and avoid
cast errors.
Testing Done: Ran the TestCanaryTool.java test suite and confirmed that
the working is correct.
Signed-off-by: Andrew Purtell <apurtell@apache.org>
This provides significant cluster start time reduction for FileSystems which do not surface locality (S3).
Signed-off-by: Andrew Purtell <apurtell@apache.org>
Upgrade commons-math:2.2 to commons-math3:3.6.1
Remove commons-math 2 specific content from LICENSE.vm
Add missing jersey-client dependency to hbase-it module
Signed-off-by: Michael Stack <stack@apache.org>
This is based on patch sent me by Balazs Meszaros. The good stuff in
here is from him. This patch does less than his ambition. It changes
Admin class only. Can work on making AsyncAdmin cohere in a follow-on.
* Deprecates getAlterStatus. Everywhere else we talk of 'modify' rather
'alter' and should use Future returned from async instead.
* isTableAvailable(TableName, byte [][]) has been deprecated to be
removed; use the overrie instead. This is a weird method.
* Changed listTableDescriptor to getDescriptor.
* Renamed other like methods to have same pattern (deprecating the old):
balancer => balance
setBalancerRunning => balancerSwitch
setNormalizerRunning => normalizerSwitch
enableCatalogJanitor => catalogJanitorSwitch
setCleanerChoreRunning => cleanerChoreSwitch
setSplitOrMergeEnabled => splitOrMergeEnabledSwitch
* Renamed (with deprecation of old) runCatalogScan => runCatalogJanitor.
* Reviewed generated javadoc and made some edits; purged reference to
hbase issues from our API, fixed param names, etc.
* Made all the enable services methods have same pattern.
* Renamed takeSnapshotAsync as snapshotAsync (with deprecation of old)
* Renamed execProcedureWithRet as execProcedureWithReturn (with
deprecation)
Signed-off-by: Michael Stack <stack@apache.org>
Includes partial backport of hbase-build-configuration module
Signed-off-by: Michael Stack <stack@apache.org>
Signed-off-by: Misty Stanley-Jones <misty@apache.org>
Javadoc for following methods are updated:
* Table.put(List<Put> puts)
* Table.delete(List<Delete> deletes)
Added @apiNote for delete regarding input list will not be modied in version 3.0.0
Signed-off-by: Michael Stack <stack@apache.org>
Main changes:
- ProcedureInfo and LockInfo were removed, we use JSON instead of them
- Procedure and LockedResource are their server side equivalent
- Procedure protobuf state_data became obsolate, it is only kept for
reading previously written WAL
- Procedure protobuf contains a state_message field, which stores the internal
state messages (Any type instead of bytes)
- Procedure.serializeStateData and deserializeStateData were changed slightly
- Procedures internal states are available on client side
- Procedures are displayed on web UI and in shell in the following jruby format:
{ ID => '1', PARENT_ID = '-1', PARAMETERS => [ ..extra state information.. ] }
Signed-off-by: Michael Stack <stack@apache.org>
* testSimpleMasterFailover - fixed and verified
* testPendingOpenOrCloseWhenMasterFailover - removed as logic is based on old code and no longer relevant. TestServerCrashProcedure tests assignments with crashing master and region servers
* testMetaInTransitionWhenMasterFailover - verified that it is fixed by patch for HBASE-18511.
Signed-off-by: Michael Stack <stack@apache.org>
Upgrade commons-collections:3.2.2 to commons-collections4:4.1
Add missing dependency for hbase-procedure, hbase-thrift
Replace CircularFifoBuffer with CircularFifoQueue in WALProcedureStore and TaskMonitor
Signed-off-by: Sean Busbey <busbey@apache.org>
Signed-off-by: Chia-Ping Tsai <chia7712@gmail.com>
(cherry picked from commit 137b105c67)
This correctly casts the operand to a long to avoid negative offsets created by sign extending the integer operand.
Signed-off-by: tedyu <yuzhihong@gmail.com>
Do a pass with dependency:analyze; remove unused and
explicity list the dependencies we exploit.
Remove the parent dependencies set which had junit, mockito,
log4j, and findbugs annotations (had to put junit back
temporarily in subsequent version of this patch TODO). Listing in
parent set meant these libs were dependencies for all modules
which in practice was not the case. Edited all modules so
those that need any from this parent set now do explicit listing.
Ran the dependency:analyze over the project. Acted on most
suggested removals and requests for explicit listing. Some
grey areas remain around transitives that come in with
hadoop -needs better excludes, another project- and that
the dependency:analyze tool is not always accurate in its
reporting.
Move Driver to be the main-class in hbase-mapreduce jar rather than
in the hbase-server jar.
Reference the hbase-server and shaded protobuf so they get bundled
when you do 'hbase mapredcp'.
classpath issue when running as a developer fixed
removed thrift webapp from server (it's not used at all, since moved to thrift webapp)
Signed-off-by: tedyu <yuzhihong@gmail.com>
- Moves out o.a.h.h.{mapred, mapreduce} to new hbase-mapreduce module which depends
on hbase-server because of classes like *Snapshot{Input,Output}Format.java, WALs, replication, etc
- hbase-backup depends on it for WALPlayer and MR job stuff
- A bunch of tools needed to be pulled into hbase-mapreduce becuase of their dependencies on MR.
These are: CompactionTool, LoadTestTool, PerformanceEvaluation, ExportSnapshot
This is better place of them than hbase-server. But ideal place would be in separate hbase-tools module.
- There were some tests in hbase-server which were digging into these tools for static util funtions or
confs. Moved these to better/easily shared place. For eg. security related stuff to HBaseKerberosUtils.
- Note that hbase-mapreduce has secondPartExecution tests. On my machine they took like 20 min, so maybe
more on apache jenkins. That's basically equal reduction of runtime of hbase-server tests, which is a
big win!
Change-Id: Ieeb7235014717ca83ee5cb13b2a27fddfa6838e8
Breaking change to our ReplicationEndpoint and BaseReplicationEndpoint.
ReplicationEndpoint implemented Guava 0.12 Service. An abstract
subclass, BaseReplicationEndpoint, provided default implementations
and facility, among other things, by extending Guava
AbstractService class.
Both of these HBase classes were marked LimitedPrivate for
REPLICATION so these classes were semi-public and made it so
Guava 0.12 was part of our API.
Having Guava in our API was a mistake. It anchors us and the
implementation of the Interface to Guava 0.12. This is untenable
given Guava changes and that the Service Interface in particular
has had extensive revamp and improvement done. We can't hold to
the Guava Interface. It changed. We can't stay on Guava 0.12;
implementors and others on our CLASSPATH won't abide being stuck
on an old Guava.
So this class makes breaking changes. The unhitching of our Interface
from Guava could only be done in a breaking manner. It undoes the
LimitedPrivate on BaseReplicationEndpoint while keeping it for the RE
Interface. It means consumers will have to copy/paste the
AbstractService-based BRE into their own codebase also supplying their
own Guava; HBase no longer 'supplies' this (our Guava usage has
been internalized, relocated).
This patch then adds into RE the basic methods RE needs of the old
Guava Service rather than return a Service to start/stop only to go
back to the RE instance to do actual work. A few method names had to
be changed so could make implementations with Guava Service internally
and not have RE method names and types clash). Semantics remained the
same otherwise. For example startAsync and stopAsync in Guava are start
and stop in RE.
* Fixed ServerCrashProcedure to set forceNewPlan to false for instances AssignProcedure. This enables balancer to find most suitable target server
* Fixed and enabled TestRestartCluster#testRetainAssignmentOnRestart on master
* Renamed method ServerName@isSameHostnameAndPort() to isSameAddress()
Signed-off-by: Michael Stack <stack@apache.org>
Instead of using an Atomic Reference to data and aborting when we detect
that new data comes in, use the native cancellation/pre-emption features
of Java Future.
Behavior prior to these changes is to call expireServer(), log exception and suppress it. These changes will result in RS receiving the YouAreDeadException and treating it as a fatal error. This 'fail fast' approach will help us stabilize the code. This behavior can be reconsidered later if necessary.
Signed-off-by: Michael Stack <stack@apache.org>
Changes the configuration hbase.balancer.tablesOnMaster from list of
table names to instead be a boolean; true if master carries
tables/regions and false if it does not.
Adds a new configuration hbase.balancer.tablesOnMaster.systemTablesOnly.
If true, hbase.balancer.tablesOnMaster is considered true but only
system tables are put on the master.
M hbase-server/src/main/java/org/apache/hadoop/hbase/master/HMaster.java
Master was claiming itself active master though it had stopped. Fix
the activeMaster flag. Set it to false on exit.
M hbase-server/src/main/java/org/apache/hadoop/hbase/master/LoadBalancer.java
Add new configs and convenience methods for getting current state of
settings.
M hbase-server/src/main/java/org/apache/hadoop/hbase/master/balancer/BaseLoadBalancer.java
Move configs up into super Interface and now the settings mean
different, remove the no longer needed processing.
* calls to methods getLowestLocalityRegionServer() & getLeastLoadedTopServerForRegion() got removed in HBASE-18164
* call to calculateRegionServerLocalities() got removed in HBASE-15486
* Some other minor improvements
Change-Id: Ib149530d8d20c019b0891c026e23180e260f59db
Signed-off-by: Apekshit Sharma <appy@apache.org>
Before this commit, BucketCache always used the default values.
This commit adds the ability to configure these values.
Signed-off-by: tedyu <yuzhihong@gmail.com>
Add in hbase-thirdparty hbase-shaded-netty instead.
s/io.netty/org.apache.hadoop.hbase.shaded.io.netty/ everywhere in hbase.
Also set a system property when running tests and when starting
hbase; required by netty so can find the relocation files in the
bundled .so.
If an unassign is unable to communicate with its target server,
expire the server and then wait on a signal from ServerCrashProcedure
before proceeding. The unassign has lock on the region so no one else
can proceed till we complete. We prevent any subsequent assign from
running until logs have been split for crashed server.
In AssignProcedure, do not assign if table is DISABLING or DISABLED.
M hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/RegionTransitionProcedure.java
Change remoteCallFailed so it returns boolean on whether implementor
wants to stay suspended or not.
M hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/UnassignProcedure.java
Doc. Also, if we are unable to talk to remote server, expire it and
then wait on SCP to wake us up after it has processed logs for failed
server.
This test as it is written currently will not work with AMv2. This needs to be re-written after HBASE-18511 is committed. Disabled the test and update JIRA to re-enable it with dependency on HBASE-18511.
Signed-off-by: Michael Stack <stack@apache.org>
* Modified AssignmentManager.processAssignQueue() method to consider only highest versioned region servers for system table regions when
destination server is not specified for them. Destination server is retained, if specified.
* Modified MoveRegionProcedure to allow null value for destination server i.e. moving a region from specific source server to non-specific/ unknown
destination server (picked by load-balancer) is supported now.
* Removed destination server selection from HMaster.checkIfShouldMoveSystemRegionAsync(), as destination server will be picked by load balancer
Signed-off-by: Michael Stack <stack@apache.org>
Contains the following commits:
HBASE-17748 Include HBase snapshots in space quotas
Introduces a new Chore in the Master which computes the size
of the snapshots included in a cluster. The size of these
snapshots are included in the table's which the snapshot was created
from HDFS usage.
Includes some test stabilization, trying to make the tests more
deterministic by ensuring we observe stable values as we know
that those values are mutable. This should help avoid problems
where size reports are delayed and we see an incomplete value.
HBASE-17752 Shell command to list snapshot sizes WRT quotas
HBASE-17840 Update hbase book to space quotas on snapshots
Other changes:
- Update corresponding tests in TestAdmin2. Removed tests centered around serverName part of old functions.
- Remove dead functions from ProtobufUtil and ServerManager
- Rename closeRegion* functions in HBTU to unassignRegion*
Change-Id: Ib9bdeb185e10750daf652be0bb328306accb73ab
Selective add of dependency on hbase-thirdparty jars.
Update to READMEs on how protobuf is done (and update to refguide).
Removed all checked in generated protobuf files. They are generated
on the fly now as part of mainline build.
This patch removes start(MasterProcedureEnv) from
ServerCrashProcedure.java which was a misnomer as a no-op. It
did not start anything.
Change-Id: I4e91864ace912e137471bfce03516746c4aff83e
Signed-off-by: Michael Stack <stack@apache.org>
Pull in guava 22.0 by using the shaded version up in new hbase-thirdparty project.
In poms, exclude guava everywhere except on hadoop-common. Do this so
we minimize transitive includes. hadoop-common is needed because hadoop
Configuration uses guava doing preconditions.
Everywhere we used guava, instead use shaded so fix a load of imports.
Stopwatch API changed as did hashing and toStringHelper which is now
in MoreObjects class. Otherwise, minimal changes to come up on 22.0
Upgrade jquery from 1.8.3 to 3.2.1 in hbase-server and hbase-thrift modules
Change-Id: I92d479e9802d954f607ba409077bc98581e9e5ca
Signed-off-by: Michael Stack <stack@apache.org>
hbase-thirdparty jars. Update to READMEs on how protobuf is done (and update to
refguide) Removed all checked in generated protobuf files. They are generatedon
the fly now as part of mainline build.
-Added new LocalityCostFunction and LocalityCandidateGenerator that
cache localities of every region/rack combination and mappings of every
region to its most local server and to its most local rack.
-Made LocalityCostFunction incremental so that it only computes locality
based on most recent region moves/swaps, rather than recomputing the
locality of every region in the cluster at every iteration of the
balancer
-Changed locality cost function to reflect the ratio of:
(Current locality) / (Best locality possible given current cluster)
Signed-off-by: tedyu <yuzhihong@gmail.com>
After enabling test hbase.master.procedure.TestServerCrashProcedure#testRecoveryAndDoubleExecutionOnRsWithMeta, this bug is found in ServerCrashProcedure
Signed-off-by: Michael Stack <stack@apache.org>
In Standalone mode with local filesystem HBase logs Warning message:Failed to invoke 'unbuffer' method in class org.apache.hadoop.fs.FSDataInputStream
Signed-off-by: Umesh Agashe <uagashe@cloudera.com>
Signed-off-by: Sean Busbey <busbey@apache.org>
-Added new LocalityCostFunction and LocalityCandidateGenerator that
cache localities of every region/rack combination and mappings of every
region to its most local server and to its most local rack.
-Made LocalityCostFunction incremental so that it only computes locality
based on most recent region moves/swaps, rather than recomputing the
locality of every region in the cluster at every iteration of the
balancer
-Changed locality cost function to reflect the ratio of:
(Current locality) / (Best locality possible given current cluster)
Signed-off-by: Sean Busbey <busbey@apache.org>
Signed-off-by: Chia-Ping Tsai <chia7712@gmail.com>
Unit test (TestAssignmentManager) uses mock which always aggregates. So added trace level log message and verified manually on a single node cluster.
Signed-off-by: Michael Stack <stack@apache.org>
Calling closeRegion() directly on remote server is not supported post-AMv2. Calling unassign() on master
Signed-off-by: Michael Stack <stack@apache.org>
This issue adds comments and a sort so system tables are queued first
(which will ensure they go out first). This should be good enough
along w/ existing scheduling mechanisms to ensure system/meta get
assigned first.
Signed-off-by: Michael Stack <stack@apache.org>