System Properties

Description

This property can be used to verify that Hazelcast members only join when their application level configuration is the same.

Controls the maximum timeout in milliseconds to wait for an invocation space to be available. The value needs to be equal to or larger than 0.

Enable back pressure.

The maximum number of concurrent invocations per partition.

Used when back pressure is enabled. The larger the sync window value, the less frequent a asynchronous backup is converted to a sync backup.

Specifies whether the cache invalidation event batch sending is enabled or not.

Defines the maximum number of cache invalidation events to be drained and sent to the event listeners in a batch.

Defines cache invalidation event batch sending frequency in seconds.

Number of threads to process query requests coming from the clients. Default count is the number of cores multiplied by 1.

Time, in seconds, after which the client connection is removed or the owner member of a client is removed from the cluster, in case of a client disconnection. Normally, the disconnection cleans all resources of a client, i.e., listeners are removed and locks/transactions are released. Using this property, the client has a window to connect back and prevent cleaning up its resources.

Maximum number of threads to process non-partition-aware client requests, like map.size(), executor tasks, etc. Default count is the number of cores multiplied by 20.

Output directory of the diagnostic log files.

Specifies whether the automatic cluster version upgrading is enabled.

When set to a value greater than 1, automatic upgrading waits to reach that cluster size to proceed.

Specifies whether diagnostics tool is enabled or not for the cluster.

Optional prefix for the diagnostics log file.

Frequency of scanning all the pending invocations in seconds. 0 means the Invocations plugin for diagnostics tool is disabled.

Threshold period, in seconds, that makes an invocation to be considered as slow.

Allowed count of diagnostic files within each roll.

Size of each diagnostic file to be rolled.

Period for which the MemberHeartbeats plugin of the diagnostics tool runs. 0 means this plugin is disabled.

Maximum allowed deviation for a member-to-member heartbeats.

Frequency, in seconds, at which the cluster information is dumped to the diagnostics log file.

Level of the comprehensive logs presented by the diagnostics tool related to what is happening in your Hazelcast system. Available values are Mandatory, Info and Debug.

Frequency, in seconds, at which the Metrics plugin dumps information to the diagnostics log file.

Period, in seconds, for which the OperationHeartbeats plugin of the diagnostics tool runs. 0 means this plugin is disabled.

Maximum allowed deviation for a member-to-member operation heartbeats.

Period, in seconds, for which the PendingInvocations plugin of the diagnostics tool runs. 0 means this plugin is disabled.

Period, in seconds, for which the SlowOperations plugin of the diagnostics tool runs. 0 means this plugin is disabled.

Period, in seconds, for which the StoreLatency plugin of the diagnostics tool runs. 0 means this plugin is disabled.

Period, in seconds, for resetting the statistics for the StoreLatency plugin of the diagnostics tool.

Specifies whether the SystemLog plugin of the diagnostics tool is enabled or not.

Specifies whether the SystemLog plugin collects information about partition migrations.

Controls whether the task scheduler removes tasks immediately upon cancellation. This is disabled by default, because it can cause severe delays on the other operations. By default all cancelled tasks are eventually get removed by the scheduler workers.

Time after which the member assumes the client is dead and closes its connections to the client.

When this property is true, if the server cannot determine the connected client version, it assumes that it has the version 3.6.x. This property is especially needed if you are using ICache (or JCache).

Timeout to connect all other cluster members when a member is joining to a cluster.

Minimum interval in milliseconds to consider a connection error as critical.

Maximum IO error count before disconnecting from a member.

Enable use of public IP address in member discovery with Discovery SPI. If you set this property to true in your source cluster, please make sure you have set the public addresses for your target members since they will be discovered using their public addresses. Otherwise, they cannot be discovered. See the Public Address section.

Hazelcast IMDG Enterprise license key.

Capacity of internal event queue.

Timeout to enqueue events to event queue.

Number of event handler threads.

Maximum wait in seconds during graceful shutdown.

Enable/disable Hazelcast’s HTTP based health check implementation. When it is enabled, you can retrieve information about your cluster’s health status (member state, cluster state, cluster size, etc.) by launching http://<your member's host IP>:5701/hazelcast/health. This property is deprecated. See the Health Check and Monitoring section.

Health monitoring logging interval in seconds. NOTE: For detailed information on the health monitoring tool, along with this and the following health monitoring related system properties, see the Health Check and Monitoring section.

Health monitoring log level. When SILENT, logs are printed only when values exceed some predefined threshold. When NOISY, logs are always printed periodically. Set OFF to turn off completely.

When the health monitoring level is SILENT, logs are printed only when the CPU usage exceeds this threshold.

When the health monitoring level is SILENT, logs are printed only when the memory usage exceeds this threshold.

Heartbeat send interval in seconds.

If enabled and is able to fetch memory statistics via Java’s OperatingSystemMXBean, it checks whether there is enough free physical memory for the requested number of bytes. If the free memory checker is disabled (false), acts as if the check is succeeded.

Specifies whether ICMP Echo Request mode for ping detector is enforced. If OS is not supported, or not configured correctly, as explained in Requirements and Linux/Unix Configuration, Hazelcast fails to start.

Specifies whether ICMP ping is enabled or not.

Interval between ping attempts in milliseconds. Default and minimum allowed value is 1 second.

Maximum ping attempts before suspecting a member.

Specifies whether Ping Failure Detector works in parallel with the other detectors.

ICMP timeout in milliseconds. This cannot be more than the value of hazelcast.icmp.interval property; it should always be smaller.

ICMP TTL (maximum numbers of hops to try).

If enabled and when a problem occurs during enabling the XML External Entity (XXE) protection, then the problem is ignored and only a warning message is logged.

This property should only be used as a last resort. Hazelcast uses the XXE protection by setting respective XML processor properties. These properties are supported in modern XML processors, e.g., the default one available in Java. An old processor, such as Xerces or Xalan, on the classpath may miss the support and throw an exception during enabling the XXE protection. Setting this system property to true allows ignoring such exceptions.

Defines the behavior for index copying on index read/write. See the Copying Indexes section.

Initial expected cluster size to wait before member to start completely.

Initial time in seconds to wait before member to start completely.

This is a property which is used internally and subject to change in the future releases.

This is a property which is used internally and subject to change in the future releases.

This is a property which is used internally and subject to change in the future releases.

If missed invalidation count is bigger than this value, relevant cached data is made unreachable.

Period for which the cluster members are scanned to compare generated invalidation events with the received ones from Near Cache.

Interval in seconds between IOBalancer executions.

Number of socket input threads.

Number of socket output threads.

Number of threads performing socket input and socket output. If, for example, the default value (3) is used, it means there are 3 threads performing input and 3 threads performing output (6 threads in total).

Type of the JCache provider. Values can be client or server.

Enable JMX agent.

Enables the legacy (for the releases before Hazelcast 3.9) member list format which is printed in the logs. The new format is introduced starting with Hazelcast 3.9 and includes member list version. Any change in the cluster, such as a member leaving or joining, increments the member list version. See the Starting the Member and Client section.

It is an overrider property for the default server socket listener’s IP address. If this property is set, then this is the address where the server socket is bound to.

It is an overrider property for the default public address to be advertised to other cluster members and clients.

All locks which are acquired without an explicit lease time use this value (in seconds) as the lease time. When you want to set an explicit lease time for your locks, you cannot set it to a longer time than this value.

Name of logging framework type to send logging events.

Notify entry listeners with predicates on map entry updates with events that match entry, update or exit from predicate value space.

Useful to deal with some possible edge cases. For example, when using EntryProcessor, without this delay, you may see an EntryProcessor running on owner partition found a key but EntryBackupProcessor did not find it on backup. As a result of this, when backup promotes to owner, you may end up with an unprocessed key.

If the collected invalidations do not reach the configured batch size, a background process sends them at this interval.

Enable or disable batching. When it is set to false, all invalidations are sent immediately.

Maximum number of invalidations in a batch.

Maximum size of the key batch sent to the partition owners for value loading and the maximum size of a key batch for which values are loaded in a single partition.

Scheduler delay for map tasks those are executed on backup members.

Maximum write-behind queue capacity per member. It is the total of all write-behind queue sizes in a member including backups. Its maximum value is Integer.MAX_VALUE. The value of this property is taken into account only if the write-coalescing element of the Map Store configuration is false. See here for the description of the write-coalescing element.

Interval at which members send master confirmation. This property is deprecated as of this (3.10) release.

Hazelcast master member (oldewst in the cluster) increments the member list version for each joining member. Then, these member list versions are used to identify the joined members with unique integers. For this algorithm to work under network partitioning scenarios, without generating duplicate member list join versions for different members, a mastership-claiming member increments the member list version as specified by this parameter, multiplied by its position in the member list. The value of the parameter must be bigger than the cluster size.

Timeout which defines when master candidate gives up waiting for response to its mastership claim. After timeout happens, non-responding member is removed from the member list.

Split-brain merge timeout for a specific target.

Join timeout, maximum time to try to join before giving.

Maximum timeout of heartbeat in seconds for a member to assume it is dead.

Max timeout of master confirmation from other members. This property is deprecated as of this (3.10) release.

Maximum wait time before join operation.

Management Center maximum visible slow operations count.

Specifies whether the URL for Management Center is enabled. This property is deprecated. See the Using the REST Endpoint Groups section.

Interval at which master member publishes a member list.

Enable Memcache client request listener service. This property is deprecated. See the Memcache Client section.

Initial run delay of split-brain/merge process in seconds.

Run interval of split-brain/merge process in seconds.

Minimum delay (in seconds) between detection of a member that has left and start of the rebalancing process.

IP address of a multicast group. If not set, configuration is read from the default Hazelcast configuration, which has the value 224.2.2.3.

Controls whether more strict checks upon BIND requests towards a cluster member are applied. The checks mainly validate the remote BIND request against the remote address as found in the socket. By default they are disabled, to avoid connectivity issues when deployed under NAT’ed infrastructure.

Maximum time a caller to wait for backup responses of an operation. After this timeout, operation response is returned to the caller even no backup response is received.

When enabled, an operation fails with IndeterminateOperationStateException, if it does not receive backup acks in time with respect to backup configuration of its data structure, or the member which owns primary replica of the target partition leaves the cluster.

Timeout to wait for a response when a remote call is sent, in milliseconds.

Number of generic operation handler threads. -1 means CPU core count / 2.

Specifies whether the response thread for internal operations on the member side are blocked or not. If you use block (the default value) the thread is blocked and need to be notified which can cause a reduction in the performance. If you use backoff there is no blocking. By enabling the backoff mode and depending on your use case, you can get a 5-10% performance improvement. However, keep in mind that this increases the CPU utilization. We recommend you to use backoff with care and if you have a tool for measuring your cluster’s performance.

Number of partition based operation handler threads. -1 means CPU core count.

Interval for syncing backup replicas in seconds.

Total partition count.

Maximum number of parallel partition backup replication operations per member. When a partition backup ownership changes or a backup inconsistency is detected, the members start to sync their backup partitions. This parameter limits the maximum running replication operations in parallel.

When enabled, which is the default behavior, partitions are migrated/replicated in small fragments instead of one big chunk. Migrating partitions in fragments reduces pressure on the memory and network, since smaller packets are created in the memory and sent through the network. Note that it can increase the migration time to complete.

Interval to run partition migration tasks in seconds.

Hazelcast allows read operations to be performed while a partition is being migrated. This can lead to stale reads for some scenarios. You can disable stale read operations by setting this system property’s value to "true". Its default value is "false", meaning that stale reads are allowed.

Timeout for partition migration tasks in seconds.

Interval for publishing partition table periodically to all cluster members in seconds.

Class name implementing com.hazelcast.core.PartitioningStrategy, which defines key to partition mapping.

The PerformanceMonitor uses a rolling file approach to prevent eating too much disk space. This property sets the maximum number of rolling files to keep on disk.

The performance monitor uses a rolling file approach to prevent eating too much disk space. This property sets the maximum size in MB for a single file. Every HazelcastInstance gets its own history of log files.

Enable the performance monitor, a tool which allows you to see internal performance metrics. These metrics are written to a dedicated log file.

The period between successive entries in the performance monitor’s log file.

Prefer IPv4 network interface when picking a local address.

Maximum value of local partitions to trigger local pre-check for TruePredicate query operations on maps.

Type of the query optimizer. For optimizations based on static rules, set the value to RULES. To disable the optimization, set the value to NONE.

Each Hazelcast member evaluates query predicates using a single thread by default. In most cases, the overhead of inter-thread communications overweight can benefit from parallel execution. When you have a large dataset and/or slow predicate, you may benefit from parallel predicate evaluations. Set to true if you are using slow predicates or have > 100,000s entries per member.

Result size limit for query operations on maps. This value defines the maximum number of returned elements for a single query result. If a query exceeds this number of elements, a QueryResultSizeExceededException is thrown. Its default value is -1, meaning it is disabled.

Enable REST client request listener service. This property is deprecated. See the Using the REST Endpoint Groups section.

Enable Hazelcast shutdownhook thread. When this is enabled, this thread terminates the Hazelcast instance without waiting to shutdown gracefully.

Specifies the behavior when JVM is exiting while the Hazelcast instance is still running. It has two values: TERMINATE and GRACEFUL. The former one terminates the Hazelcast instance immediately. The latter, GRACEFUL, initiates the graceful shutdown which can significantly slow down the JVM exit process, but it tries to retain data safety. Note that you should always shutdown Hazelcast explicitly via using the method HazelcastInstance.shutdown(). It’s not recommended to rely on the shutdown hook, this is a last-effort measure.

Enables/disables the SlowOperationDetector.

Purge interval for slow operation logs.

Defines the retention time of invocations in slow operation logs. If an invocation is older than this value, it is purged from the log to prevent unlimited memory usage. When all invocations are purged from a log, the log itself is deleted.

Defines if the stacktraces of slow operations are logged in the log file. Stack traces are always reported to the Management Center, but by default, they are not printed to keep the log size small.

Defines a threshold above which a running operation in OperationService is considered to be slow. These operations log a warning and are shown in the Management Center with detailed information, e.g., stacktrace.

Bind both server-socket and client-sockets to any local interface.

Specifies whether the byte buffers used in the socket should be a direct byte buffer (true) or a regular one (false). When it is set to true, Hazelcast internally uses the method ByteBuffer.allocateDirect (instead of ByteBuffer.allocate) which makes use of the off-heap and may skip the memory copying when performing socket I/O operations. See here for more information.

Bind client socket to an interface when connecting to a remote server socket. When set to false, client socket is not bound to any interface.

Bind client-sockets to any local interface. If not set, hazelcast.socket.bind.any is used as the default.

Hazelcast creates all connections with receive buffer size set according to the hazelcast.socket.receive.buffer.size. When it detects a connection opened by a client, then it adjusts the receive buffer size according to this property. It is in kilobytes and its default value is -1.

Hazelcast creates all connections with send buffer size set according to the hazelcast.socket.send.buffer.size. When it detects a connection opened by a client, then it adjusts the send buffer size according to this property. It is in kilobytes and its default value is -1.

Socket connection timeout in seconds. Socket.connect() is blocked until either connection is established or connection is refused or this timeout passes. Default is 0, means infinite.

Socket set keep alive (SO_KEEPALIVE).

Set socket SO_LINGER option.

Socket set TCP no delay.

Socket receive buffer (SO_RCVBUF) size in KB. If you have a very fast network, e.g., 10gbit) and/or you have large entries, then you may benefit from increasing sender/receiver buffer sizes. Use this property and the next one below tune the size.

Socket send buffer (SO_SNDBUF) size in KB.

Bind server-socket to any local interface. If not set, hazelcast.socket.bind.any is used as the default.

The number of incremental ports, starting with the port number defined in the network configuration, that is used to connect to a host (which is defined without a port in TCP/IP member list while a member is searching for a cluster).

"auto" (the default value) automatically detects whether the usage of Unsafe is suitable for a given platform. "disabled" explicitly disables the Unsafe usage in your platform. "enforced" enforces the usage of Unsafe even if your platform does not support it. This property can only be set by passing a JVM-wide system property.

Enable or disable the sending of phone home data to Hazelcast’s phone home server.

Wait time before join operation.

Configures WAN replication for IMap on the PASSIVE cluster to remove entries using delete instead of remove and when using com.hazelcast.enterprise.wan.replication.WanBatchReplication as an endpoint implementation. The member which receives the event batch in the PASSIVE cluster dispatches WAN events to the partition owners as map merge and remove operations. When using remove operations, the old entry value is sent from the partition owner to the caller even though the caller does not use the old value. This can also lead to issues if the PASSIVE cluster does not contain the class definition for the entry value as the value tries to get deserialized, causing ClassNotFoundExceptions. You can switch to using map remove instead on the PASSIVE cluster with this property. This both saves the bandwidth and avoid the exceptions.