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- Metric Types
- Table Metrics
- Keyspace Metrics
- ThreadPool Metrics
- Client Request Metrics
- Cache Metrics
- CQL Metrics
- DroppedMessage Metrics
- Streaming Metrics
- Compaction Metrics
- CommitLog Metrics
- Storage Metrics
- HintedHandoff Metrics
- HintsService Metrics
- SSTable Index Metrics
- BufferPool Metrics
- Client Metrics
- Batch Metrics
- JVM Metrics
- JMX
- Metric Reporters
Monitoring
Metrics in Cassandra are managed using the Dropwizard Metrics library. Metrics can be queried via JMX, Virtual Tables, or pushed to external monitoring systems using a variety of built-in reporters or third-party reporter plug-ins.
Metrics are collected for a single node. It’s up to the operator to use an external monitoring system to aggregate them.
Metric Types
All metrics reported by cassandra fit into one of the following types.
Gauge
An instantaneous measurement of a value.
Counter
A gauge for an AtomicLong instance. Typically this is consumed by monitoring the change since the last call to see if there is a large increase compared to the norm.
Histogram
Measures the statistical distribution of values in a stream of data. + In addition to minimum, maximum, mean, etc., it also measures median, 75th, 90th, 95th, 98th, 99th, and 99.9th percentiles.
Timer
Measures both the rate that a particular piece of code is called and the histogram of its duration.
Latency
Special type that tracks latency (in microseconds) with a Timer plus a Counter that tracks the total latency accrued since starting. The former is useful if you track the change in total latency since the last check. Each metric name of this type will have ‘Latency’ and ‘TotalLatency’ appended to it.
Meter
A meter metric which measures mean throughput and one-, five-, and fifteen-minute exponentially-weighted moving average throughputs.
Table Metrics
Each table in Cassandra has metrics responsible for tracking its state and performance.
The metric names are all appended with the specific Keyspace and Table name.
Reported name format:
Metric Name
org.apache.cassandra.metrics.Table.<MetricName>.<Keyspace>.<Table>
JMX MBean
org.apache.cassandra.metrics:type=Table keyspace=<Keyspace> scope=<Table> name=<MetricName>
There is a special table called ‘all’ without a keyspace. This represents the aggregation of metrics across all tables and keyspaces on the node. |
| Name | Type | Description |
|---|---|---|
MemtableOnHeapSize | Gauge<Long> | Total amount of data stored in the memtable that resides on-heap, including column related overhead and partitions overwritten. |
MemtableOffHeapSize | Gauge<Long> | Total amount of data stored in the memtable that resides off-heap, including column related overhead and partitions overwritten. |
MemtableLiveDataSize | Gauge<Long> | Total amount of live data stored in the memtable, excluding any data structure overhead. |
AllMemtablesOnHeapSize | Gauge<Long> | Total amount of data stored in the memtables (2i and pending flush memtables included) that resides on-heap. |
AllMemtablesOffHeapSize | Gauge<Long> | Total amount of data stored in the memtables (2i and pending flush memtables included) that resides off-heap. |
AllMemtablesLiveDataSize | Gauge<Long> | Total amount of live data stored in the memtables (2i and pending flush memtables included) that resides off-heap, excluding any data structure overhead. |
MemtableColumnsCount | Gauge<Long> | Total number of columns present in the memtable. |
MemtableSwitchCount | Counter | Number of times flush has resulted in the memtable being switched out. |
CompressionRatio | Gauge<Double> | Current compression ratio for all SSTables. |
EstimatedPartitionSizeHistogram | Gauge<long[]> | Histogram of estimated partition size (in bytes). |
EstimatedPartitionCount | Gauge<Long> | Approximate number of keys in table. |
EstimatedColumnCountHistogram | Gauge<long[]> | Histogram of estimated number of columns. |
SSTablesPerReadHistogram | Histogram | Histogram of the number of sstable data files accessed per single partition read. SSTables skipped due to Bloom Filters, min-max key or partition index lookup are not taken into acoount. |
ReadLatency | Latency | Local read latency for this table. |
RangeLatency | Latency | Local range scan latency for this table. |
WriteLatency | Latency | Local write latency for this table. |
CoordinatorReadLatency | Timer | Coordinator read latency for this table. |
CoordinatorWriteLatency | Timer | Coordinator write latency for this table. |
CoordinatorScanLatency | Timer | Coordinator range scan latency for this table. |
PendingFlushes | Counter | Estimated number of flush tasks pending for this table. |
BytesFlushed | Counter | Total number of bytes flushed since server [re]start. |
CompactionBytesWritten | Counter | Total number of bytes written by compaction since server [re]start. |
PendingCompactions | Gauge<Integer> | Estimate of number of pending compactions for this table. |
LiveSSTableCount | Gauge<Integer> | Number of SSTables on disk for this table. |
LiveDiskSpaceUsed | Counter | Disk space used by SSTables belonging to this table (in bytes). |
TotalDiskSpaceUsed | Counter | Total disk space used by SSTables belonging to this table, including obsolete ones waiting to be GC’d. |
MaxSSTableSize | Gauge<Long> | Maximum size of SSTable of this table - the physical size on disk of all components for such SSTable in bytes. Equals to zero if there is not any SSTable on disk. |
MaxSSTableDuration | Gauge<Long> | Maximum duration in milliseconds of an SSTable for this table, computed as |
MinPartitionSize | Gauge<Long> | Size of the smallest compacted partition (in bytes). |
MaxPartitionSize | Gauge<Long> | Size of the largest compacted partition (in bytes). |
MeanPartitionSize | Gauge<Long> | Size of the average compacted partition (in bytes). |
BloomFilterFalsePositives | Gauge<Long> | Number of false positives on table’s bloom filter. |
BloomFilterFalseRatio | Gauge<Double> | False positive ratio of table’s bloom filter. |
BloomFilterDiskSpaceUsed | Gauge<Long> | Disk space used by bloom filter (in bytes). |
BloomFilterOffHeapMemoryUsed | Gauge<Long> | Off-heap memory used by bloom filter. |
IndexSummaryOffHeapMemoryUsed | Gauge<Long> | Off-heap memory used by index summary. |
CompressionMetadataOffHeapMemoryUsed | Gauge<Long> | Off-heap memory used by compression meta data. |
KeyCacheHitRate | Gauge<Double> | Key cache hit rate for this table. |
TombstoneScannedHistogram | Histogram | Histogram of tombstones scanned in queries on this table. |
LiveScannedHistogram | Histogram | Histogram of live cells scanned in queries on this table. |
ColUpdateTimeDeltaHistogram | Histogram | Histogram of column update time delta on this table. |
ViewLockAcquireTime | Timer | Time taken acquiring a partition lock for materialized view updates on this table. |
ViewReadTime | Timer | Time taken during the local read of a materialized view update. |
TrueSnapshotsSize | Gauge<Long> | Disk space used by snapshots of this table including all SSTable components. |
RowCacheHitOutOfRange | Counter | Number of table row cache hits that do not satisfy the query filter, thus went to disk. |
RowCacheHit | Counter | Number of table row cache hits. |
RowCacheMiss | Counter | Number of table row cache misses. |
CasPrepare | Latency | Latency of paxos prepare round. |
CasPropose | Latency | Latency of paxos propose round. |
CasCommit | Latency | Latency of paxos commit round. |
PercentRepaired | Gauge<Double> | Percent of table data that is repaired on disk. |
BytesRepaired | Gauge<Long> | Size of table data repaired on disk |
BytesUnrepaired | Gauge<Long> | Size of table data unrepaired on disk |
BytesPendingRepair | Gauge<Long> | Size of table data isolated for an ongoing incremental repair |
SpeculativeRetries | Counter | Number of times speculative retries were sent for this table. |
SpeculativeFailedRetries | Counter | Number of speculative retries that failed to prevent a timeout |
SpeculativeInsufficientReplicas | Counter | Number of speculative retries that couldn’t be attempted due to lack of replicas |
SpeculativeSampleLatencyNanos | Gauge<Long> | Number of nanoseconds to wait before speculation is attempted. Value may be statically configured or updated periodically based on coordinator latency. |
AnticompactionTime | Timer | Time spent anticompacting before a consistent repair. |
ValidationTime | Timer | Time spent doing validation compaction during repair. |
SyncTime | Timer | Time spent doing streaming during repair. |
BytesValidated | Histogram | Histogram over the amount of bytes read during validation. |
PartitionsValidated | Histogram | Histogram over the number of partitions read during validation. |
BytesAnticompacted | Counter | How many bytes we anticompacted. |
BytesMutatedAnticompaction | Counter | How many bytes we avoided anticompacting because the sstable was fully contained in the repaired range. |
MutatedAnticompactionGauge | Gauge<Double> | Ratio of bytes mutated vs total bytes repaired. |
Keyspace Metrics
Each keyspace in Cassandra has metrics responsible for tracking its state and performance.
Most of these metrics are the same as the Table Metrics above, only they are aggregated at the Keyspace level. The keyspace specific metrics are specified in the table below.
Reported name format:
Metric Name
org.apache.cassandra.metrics.keyspace.<MetricName>.<Keyspace>
JMX MBean
org.apache.cassandra.metrics:type=Keyspace scope=<Keyspace> name=<MetricName>
| Name | Type | Description |
|---|---|---|
WriteFailedIdeaCL | Counter | Number of writes that failed to achieve the configured ideal consistency level or 0 if none is configured |
IdealCLWriteLatency | Latency | Coordinator latency of writes at the configured ideal consistency level. No values are recorded if ideal consistency level is not configured |
RepairTime | Timer | Total time spent as repair coordinator. |
RepairPrepareTime | Timer | Total time spent preparing for repair. |
ThreadPool Metrics
Cassandra splits work of a particular type into its own thread pool. This provides back-pressure and asynchrony for requests on a node. It’s important to monitor the state of these thread pools since they can tell you how saturated a node is.
The metric names are all appended with the specific ThreadPool name. The thread pools are also categorized under a specific type.
Reported name format:
Metric Name
org.apache.cassandra.metrics.ThreadPools.<MetricName>.<Path>.<ThreadPoolName>
JMX MBean
org.apache.cassandra.metrics:type=ThreadPools path=<Path> scope=<ThreadPoolName> name=<MetricName>
| Name | Type | Description |
|---|---|---|
ActiveTasks | Gauge<Integer> | Number of tasks being actively worked on by this pool. |
PendingTasks | Gauge<Integer> | Number of queued tasks queued up on this pool. |
CompletedTasks | Counter | Number of tasks completed. |
TotalBlockedTasks | Counter | Number of tasks that were blocked due to queue saturation. |
CurrentlyBlockedTask | Counter | Number of tasks that are currently blocked due to queue saturation but on retry will become unblocked. |
MaxPoolSize | Gauge<Integer> | The maximum number of threads in this pool. |
MaxTasksQueued | Gauge<Integer> | The maximum number of tasks queued before a task get blocked. |
The following thread pools can be monitored.
| Name | Type | Description |
|---|---|---|
Native-Transport-Requests | transport | Handles client CQL requests |
CounterMutationStage | request | Responsible for counter writes |
ViewMutationStage | request | Responsible for materialized view writes |
MutationStage | request | Responsible for all other writes |
ReadRepairStage | request | ReadRepair happens on this thread pool |
ReadStage | request | Local reads run on this thread pool |
RequestResponseStage | request | Coordinator requests to the cluster run on this thread pool |
AntiEntropyStage | internal | Builds merkle tree for repairs |
CacheCleanupExecutor | internal | Cache maintenance performed on this thread pool |
CompactionExecutor | internal | Compactions are run on these threads |
GossipStage | internal | Handles gossip requests |
HintsDispatcher | internal | Performs hinted handoff |
InternalResponseStage | internal | Responsible for intra-cluster callbacks |
MemtableFlushWriter | internal | Writes memtables to disk |
MemtablePostFlush | internal | Cleans up commit log after memtable is written to disk |
MemtableReclaimMemory | internal | Memtable recycling |
MigrationStage | internal | Runs schema migrations |
MiscStage | internal | Misceleneous tasks run here |
PendingRangeCalculator | internal | Calculates token range |
PerDiskMemtableFlushWriter_0 | internal | Responsible for writing a spec (there is one of these per disk 0-N) |
Sampler | internal | Responsible for re-sampling the index summaries of SStables |
SecondaryIndexManagement | internal | Performs updates to secondary indexes |
ValidationExecutor | internal | Performs validation compaction or scrubbing |
ViewBuildExecutor | internal | Performs materialized views initial build |
Client Request Metrics
Client requests have their own set of metrics that encapsulate the work happening at coordinator level.
Different types of client requests are broken down by RequestType.
Reported name format:
Metric Name
org.apache.cassandra.metrics.ClientRequest.<MetricName>.<RequestType>
JMX MBean
org.apache.cassandra.metrics:type=ClientRequest scope=<RequestType> name=<MetricName>
RequestType
CASRead
Description
Metrics related to transactional read requests.
Metrics
| Name | Type | Description |
|---|---|---|
Timeouts | Counter | Number of timeouts encountered. |
Failures | Counter | Number of transaction failures encountered. |
Latency | Transaction read latency. | |
Unavailables | Counter | Number of unavailable exceptions encountered. |
UnfinishedCommit | Counter | Number of transactions that were committed on read. |
ConditionNotMet | Counter | Number of transaction preconditions did not match current values. |
ContentionHistogram | Histogram | How many contended reads were encountered |
RequestType
CASWrite
Description
Metrics related to transactional write requests.
Metrics
| Name | Type | Description |
|---|---|---|
Timeouts | Counter | Number of timeouts encountered. |
Failures | Counter | Number of transaction failures encountered. |
Latency | Transaction write latency. | |
Unavailables | Counter | Number of unavailable exceptions encountered. |
UnfinishedCommit | Counter | Number of transactions that were committed on write. |
ConditionNotMet | Counter | Number of transaction preconditions did not match current values. |
ContentionHistogram | Histogram | How many contended writes were encountered |
MutationSizeHistogram | Histogram | Total size in bytes of the requests mutations. |
RequestType
Read
Description
Metrics related to standard read requests.
Metrics
| Name | Type | Description |
|---|---|---|
Timeouts | Counter | Number of timeouts encountered. |
Failures | Counter | Number of read failures encountered. |
Latency | Read latency. | |
Unavailables | Counter | Number of unavailable exceptions encountered. |
RequestType
RangeSlice
Description
Metrics related to token range read requests.
Metrics
| Name | Type | Description |
|---|---|---|
Timeouts | Counter | Number of timeouts encountered. |
Failures | Counter | Number of range query failures encountered. |
Latency | Range query latency. | |
Unavailables | Counter | Number of unavailable exceptions encountered. |
RequestType
Write
Description
Metrics related to regular write requests.
Metrics
| Name | Type | Description |
|---|---|---|
Timeouts | Counter | Number of timeouts encountered. |
Failures | Counter | Number of write failures encountered. |
Latency | Write latency. | |
Unavailables | Counter | Number of unavailable exceptions encountered. |
MutationSizeHistogram | Histogram | Total size in bytes of the requests mutations. |
RequestType
ViewWrite
Description
Metrics related to materialized view write wrtes.
Metrics
| Timeouts | Counter | Number of timeouts encountered. |
|---|---|---|
Failures | Counter | Number of transaction failures encountered. |
Unavailables | Counter | Number of unavailable exceptions encountered. |
ViewReplicasAttempted | Counter | Total number of attempted view replica writes. |
ViewReplicasSuccess | Counter | Total number of succeded view replica writes. |
ViewPendingMutations | Gauge<Long> | ViewReplicasAttempted - ViewReplicasSuccess. |
ViewWriteLatency | Timer | Time between when mutation is applied to base table and when CL.ONE is achieved on view. |
Cache Metrics
Cassandra caches have metrics to track the effectivness of the caches. Though the Table Metrics might be more useful.
Reported name format:
Metric Name
org.apache.cassandra.metrics.Cache.<MetricName>.<CacheName>
JMX MBean
org.apache.cassandra.metrics:type=Cache scope=<CacheName> name=<MetricName>
| Name | Type | Description |
|---|---|---|
Capacity | Gauge<Long> | Cache capacity in bytes. |
Entries | Gauge<Integer> | Total number of cache entries. |
FifteenMinuteCacheHitRate | Gauge<Double> | 15m cache hit rate. |
FiveMinuteCacheHitRate | Gauge<Double> | 5m cache hit rate. |
OneMinuteCacheHitRate | Gauge<Double> | 1m cache hit rate. |
HitRate | Gauge<Double> | All time cache hit rate. |
Hits | Meter | Total number of cache hits. |
Misses | Meter | Total number of cache misses. |
MissLatency | Timer | Latency of misses. |
Requests | Gauge<Long> | Total number of cache requests. |
Size | Gauge<Long> | Total size of occupied cache, in bytes. |
The following caches are covered:
| Name | Description |
|---|---|
CounterCache | Keeps hot counters in memory for performance. |
ChunkCache | In process uncompressed page cache. |
KeyCache | Cache for partition to sstable offsets. |
RowCache | Cache for rows kept in memory. |
Misses and MissLatency are only defined for the ChunkCache |
CQL Metrics
Metrics specific to CQL prepared statement caching.
Reported name format:
Metric Name
org.apache.cassandra.metrics.CQL.<MetricName>
JMX MBean
org.apache.cassandra.metrics:type=CQL name=<MetricName>
| Name | Type | Description |
|---|---|---|
PreparedStatementsCount | Gauge<Integer> | Number of cached prepared statements. |
PreparedStatementsEvicted | Counter | Number of prepared statements evicted from the prepared statement cache |
PreparedStatementsExecuted | Counter | Number of prepared statements executed. |
RegularStatementsExecuted | Counter | Number of non prepared statements executed. |
PreparedStatementsRatio | Gauge<Double> | Percentage of statements that are prepared vs unprepared. |
DroppedMessage Metrics
Metrics specific to tracking dropped messages for different types of requests. Dropped writes are stored and retried by Hinted Handoff
Reported name format:
Metric Name
org.apache.cassandra.metrics.DroppedMessage.<MetricName>.<Type>
JMX MBean
org.apache.cassandra.metrics:type=DroppedMessage scope=<Type> name=<MetricName>
| Name | Type | Description |
|---|---|---|
CrossNodeDroppedLatency | Timer | The dropped latency across nodes. |
InternalDroppedLatency | Timer | The dropped latency within node. |
Dropped | Meter | Number of dropped messages. |
The different types of messages tracked are:
| Name | Description |
|---|---|
BATCH_STORE | Batchlog write |
BATCH_REMOVE | Batchlog cleanup (after succesfully applied) |
COUNTER_MUTATION | Counter writes |
HINT | Hint replay |
MUTATION | Regular writes |
READ | Regular reads |
READ_REPAIR | Read repair |
PAGED_SLICE | Paged read |
RANGE_SLICE | Token range read |
REQUEST_RESPONSE | RPC Callbacks |
_TRACE | Tracing writes |
Streaming Metrics
Metrics reported during Streaming operations, such as repair, bootstrap, rebuild.
These metrics are specific to a peer endpoint, with the source node being the node you are pulling the metrics from.
Reported name format:
Metric Name
org.apache.cassandra.metrics.Streaming.<MetricName>.<PeerIP>
JMX MBean
org.apache.cassandra.metrics:type=Streaming scope=<PeerIP> name=<MetricName>
| Name | Type | Description |
|---|---|---|
IncomingBytes | Counter | Number of bytes streamed to this node from the peer. |
OutgoingBytes | Counter | Number of bytes streamed to the peer endpoint from this node. |
Compaction Metrics
Metrics specific to Compaction work.
Reported name format:
Metric Name
org.apache.cassandra.metrics.Compaction.<MetricName>
JMX MBean
org.apache.cassandra.metrics:type=Compaction name=<MetricName>
| Name | Type | Description |
|---|---|---|
BytesCompacted | Counter | Total number of bytes compacted since server [re]start. |
PendingTasks | Gauge<Integer> | Estimated number of compactions remaining to perform. |
CompletedTasks | Gauge<Long> | Number of completed compactions since server [re]start. |
TotalCompactionsCompleted | Meter | Throughput of completed compactions since server [re]start. |
PendingTasksByTableName | Gauge<Map<String, Map<String, Integer>>> | Estimated number of compactions remaining to perform, grouped by keyspace and then table name. This info is also kept in |
CommitLog Metrics
Metrics specific to the CommitLog
Reported name format:
Metric Name
org.apache.cassandra.metrics.CommitLog.<MetricName>
JMX MBean
org.apache.cassandra.metrics:type=CommitLog name=<MetricName>
| Name | Type | Description |
|---|---|---|
CompletedTasks | Gauge<Long> | Total number of commit log messages written since [re]start. |
PendingTasks | Gauge<Long> | Number of commit log messages written but yet to be fsync’d. |
TotalCommitLogSize | Gauge<Long> | Current size, in bytes, used by all the commit log segments. |
WaitingOnSegmentAllocation | Timer | Time spent waiting for a CommitLogSegment to be allocated - under normal conditions this should be zero. |
WaitingOnCommit | Timer | The time spent waiting on CL fsync; for Periodic this is only occurs when the sync is lagging its sync interval. |
Storage Metrics
Metrics specific to the storage engine.
Reported name format:
Metric Name
org.apache.cassandra.metrics.Storage.<MetricName>
JMX MBean
org.apache.cassandra.metrics:type=Storage name=<MetricName>
| Name | Type | Description |
|---|---|---|
Exceptions | Counter | Number of internal exceptions caught. Under normal exceptions this should be zero. |
Load | Counter | Size, in bytes, of the on disk data size this node manages. |
TotalHints | Counter | Number of hint messages written to this node since [re]start. Includes one entry for each host to be hinted per hint. |
TotalHintsInProgress | Counter | Number of hints attemping to be sent currently. |
HintedHandoff Metrics
Metrics specific to Hinted Handoff. There are also some metrics related to hints tracked in Storage Metrics
These metrics include the peer endpoint in the metric name
Reported name format:
Metric Name
org.apache.cassandra.metrics.HintedHandOffManager.<MetricName>
JMX MBean
org.apache.cassandra.metrics:type=HintedHandOffManager name=<MetricName>
| Name | Type | Description |
|---|---|---|
Hints_created-<PeerIP> |
|
|
Hints_not_stored-<PeerIP> |
|
|
HintsService Metrics
Metrics specific to the Hints delivery service. There are also some metrics related to hints tracked in Storage Metrics
These metrics include the peer endpoint in the metric name
Reported name format:
Metric Name
org.apache.cassandra.metrics.HintsService.<MetricName>
JMX MBean
org.apache.cassandra.metrics:type=HintsService name=<MetricName>
| Name | Type | Description |
|---|---|---|
HintsSucceeded |
|
|
HintsFailed |
|
|
HintsTimedOut |
|
|
Hint_delays | Histogram | Histogram of hint delivery delays (in milliseconds) |
Hint_delays-<PeerIP> | Histogram | Histogram of hint delivery delays (in milliseconds) per peer |
SSTable Index Metrics
Metrics specific to the SSTable index metadata.
Reported name format:
Metric Name
org.apache.cassandra.metrics.Index.<MetricName>.RowIndexEntry
JMX MBean
org.apache.cassandra.metrics:type=Index scope=RowIndexEntry name=<MetricName>
| Name | Type | Description |
|---|---|---|
IndexedEntrySize | Histogram | Histogram of the on-heap size, in bytes, of the index across all SSTables. |
IndexInfoCount | Histogram | Histogram of the number of on-heap index entries managed across all SSTables. |
IndexInfoGets | Histogram | Histogram of the number index seeks performed per SSTable. |
BufferPool Metrics
Metrics specific to the internal recycled buffer pool Cassandra manages. This pool is meant to keep allocations and GC lower by recycling on and off heap buffers.
Reported name format:
Metric Name
org.apache.cassandra.metrics.BufferPool.<MetricName>
JMX MBean
org.apache.cassandra.metrics:type=BufferPool name=<MetricName>
| Name | Type | Description |
|---|---|---|
Size | Gauge<Long> | Size, in bytes, of the managed buffer pool |
Misses | Meter |
|
Client Metrics
Metrics specifc to client managment.
Reported name format:
Metric Name
org.apache.cassandra.metrics.Client.<MetricName>
JMX MBean
org.apache.cassandra.metrics:type=Client name=<MetricName>
| Name | Type | Description |
|---|---|---|
connectedNativeClients | Gauge<Integer> | Number of clients connected to this nodes native protocol server |
connections | Gauge<List<Map<String, String>> | List of all connections and their state information |
connectedNativeClientsByUser | Gauge<Map<String, Int> | Number of connnective native clients by username |
Batch Metrics
Metrics specifc to batch statements.
Reported name format:
Metric Name
org.apache.cassandra.metrics.Batch.<MetricName>
JMX MBean
org.apache.cassandra.metrics:type=Batch name=<MetricName>
| Name | Type | Description |
|---|---|---|
PartitionsPerCounterBatch | Histogram | Distribution of the number of partitions processed per counter batch |
PartitionsPerLoggedBatch | Histogram | Distribution of the number of partitions processed per logged batch |
PartitionsPerUnloggedBatch | Histogram | Distribution of the number of partitions processed per unlogged batch |
JVM Metrics
JVM metrics such as memory and garbage collection statistics can either be accessed by connecting to the JVM using JMX or can be exported using Metric Reporters.
BufferPool
Metric Name
jvm.buffers.<direct|mapped>.<MetricName>
JMX MBean
java.nio:type=BufferPool name=<direct|mapped>
| Name | Type | Description |
|---|---|---|
Capacity | Gauge<Long> | Estimated total capacity of the buffers in this pool |
Count | Gauge<Long> | Estimated number of buffers in the pool |
Used | Gauge<Long> | Estimated memory that the Java virtual machine is using for this buffer pool |
FileDescriptorRatio
Metric Name
jvm.fd.<MetricName>
JMX MBean
java.lang:type=OperatingSystem name=<OpenFileDescriptorCount|MaxFileDescriptorCount>
| Name | Type | Description |
|---|---|---|
Usage | Ratio | Ratio of used to total file descriptors |
GarbageCollector
Metric Name
jvm.gc.<gc_type>.<MetricName>
JMX MBean
java.lang:type=GarbageCollector name=<gc_type>
| Name | Type | Description |
|---|---|---|
Count | Gauge<Long> | Total number of collections that have occurred |
Time | Gauge<Long> | Approximate accumulated collection elapsed time in milliseconds |
Memory
Metric Name
jvm.memory.<heap/non-heap/total>.<MetricName>
JMX MBean
java.lang:type=Memory
Committed | Gauge<Long> | Amount of memory in bytes that is committed for the JVM to use |
Init | Gauge<Long> | Amount of memory in bytes that the JVM initially requests from the OS |
Max | Gauge<Long> | Maximum amount of memory in bytes that can be used for memory management |
Usage | Ratio | Ratio of used to maximum memory |
Used | Gauge<Long> | Amount of used memory in bytes |
MemoryPool
Metric Name
jvm.memory.pools.<memory_pool>.<MetricName>
JMX MBean
java.lang:type=MemoryPool name=<memory_pool>
Committed | Gauge<Long> | Amount of memory in bytes that is committed for the JVM to use |
Init | Gauge<Long> | Amount of memory in bytes that the JVM initially requests from the OS |
Max | Gauge<Long> | Maximum amount of memory in bytes that can be used for memory management |
Usage | Ratio | Ratio of used to maximum memory |
Used | Gauge<Long> | Amount of used memory in bytes |
JMX
Any JMX based client can access metrics from cassandra.
If you wish to access JMX metrics over http it’s possible to download Mx4jTool and place mx4j-tools.jar into the classpath. On startup you will see in the log:
HttpAdaptor version 3.0.2 started on port 8081
To choose a different port (8081 is the default) or a different listen address (0.0.0.0 is not the default) edit conf/cassandra-env.sh and uncomment:
#MX4J_ADDRESS="-Dmx4jaddress=0.0.0.0"#MX4J_PORT="-Dmx4jport=8081"
Metric Reporters
As mentioned at the top of this section the Cassandra metrics can be exported to a number of external monitoring system using built-in reporters or third-party reporter plugins.
