Configuring the Jet Engine
This section describes Hazelcast’s Jet engine specific configuration. See the Configuration Options section to learn more about the configuration files and options.
Enabling the Jet Engine
You can enable Hazelcast’s Jet engine using the following configurations:
<hazelcast>
...
<jet enabled="true" ...>
...
</jet>
</hazelcast>
hazelcast:
...
jet:
enabled: true
...
...
Config config = new Config();
config.getJetConfig().setEnabled(true);
HazelcastInstance instance = createHazelcastInstance(config);
...
Note that, Hazelcast’s Jet engine is disabled by default when you use Hazelcast
within the Java context; that is, hazelcast.jar
. When using Hazelcast ZIP/TAR distributions
or Docker and Kubernetes distribution, Jet engine is enabled by default. See the
Security Defaults section for information about
the enabled/disabled features for different Hazelcast distributions.
Enabling Resource Uploads
You can enable resource uploads for Jet engine jobs using the following configurations:
<hazelcast>
...
<jet enabled="true" resource-upload-enabled="true">
...
</jet>
</hazelcast>
hazelcast:
...
jet:
enabled: true
resource-upload-enabled: true
...
...
Config config = new Config();
config.getJetConfig().setEnabled(true).setResourceUploadEnabled(true);
HazelcastInstance instance = createHazelcastInstance(config);
...
By default, resource uploading for Jet engine jobs is disabled.
List of Configuration Options
The hazelcast-full-example configuration files (available as YAML or XML) available in your distribution and linked from Declarative Configuration include a description of all configuration options. The configuration options for Jet engine are also listed below:
Option | Default | Description | ||
---|---|---|---|---|
|
number of cores |
The number of threads Jet creates in its cooperative multithreading pool. |
||
|
100 |
The Jet engine uses a flow control mechanism between cluster members to prevent a slower vertex from getting overflowed with data from a faster upstream vertex. Each receiver regularly reports to each sender how much more data it may send over a given DAG edge. This method sets the duration (in milliseconds) of the interval between flow-control packets. |
||
|
1 |
The number of synchronous backups to configure on the IMap that Jet needs internally to store job metadata and snapshots. The maximum allowed value is 6. |
||
|
10,000 |
The delay after which the auto-scaled jobs restart if a new member joins the cluster. It has no effect on jobs with auto scaling disabled. |
||
|
false |
Specifies whether the Lossless Cluster Restart feature is enabled.
With this feature, you can restart the whole cluster without losing the
jobs and their state. It is implemented on top of Hazelcast’s Persistence
feature, which persists the data to disk. You need to have
the Hazelcast Enterprise edition and configure Hazelcast’s Persistence to
use this feature. The default value is |
||
|
|
Specifies the maximum number of records that can be accumulated by any single
processor instance. Operations like grouping, sorting or joining require certain amount of
records to be accumulated before they can proceed. You can set this option
to reduce the probability of
|
||
|
Sets the capacity of processor-to-processor concurrent queues. The value is rounded upwards to the next power of 2. |
|||
|
For a distributed edge, data is sent to a remote member via Hazelcast network packets. Each packet is dedicated to the data of a single edge, but may contain any number of data items. This setting limits the size of the packet in bytes. Packets should be large enough to drown out any fixed overheads, but small enough to allow good interleaving with other packets. |
|||
|
Sets the scaling factor used by the adaptive receive window sizing function. |
The following is an example declarative configuration:
<hazelcast>
<jet enabled="true" resource-upload-enabled="true">
<cooperative-thread-count>4</cooperative-thread-count>
<flow-control-period>100</flow-control-period>
<backup-count>1</backup-count>
<scale-up-delay-millis>10000</scale-up-delay-millis>
<lossless-restart-enabled>false</lossless-restart-enabled>
<max-processor-accumulated-records>1000000000</max-processor-accumulated-records>
<edge-defaults>
<queue-size>1024</queue-size>
<packet-size-limit>16384</packet-size-limit>
<receive-window-multiplier>3</receive-window-multiplier>
</edge-defaults>
</jet>
</hazelcast>
hazelcast:
jet:
enabled: true
resource-upload-enabled: true
cooperative-thread-count: 4
flow-control-period: 100
backup-count: 1
scale-up-delay-millis: 10000
lossless-restart-enabled: false
max-processor-accumulated-records: 1000000000
edge-defaults:
queue-size: 1024
packet-size-limit: 16384
receive-window-multiplier: 3
List of Configuration Properties
Configuration properties can either be configured through Java system
properties (specified using the standard -Dproperty=value
) syntax
before application startup or under the properties:
inside the yaml
file:
hazelcast:
properties:
jet.idle.cooperative.min.microseconds: 50
jet.idle.cooperative.max.microseconds: 500
jet.idle.noncooperative.min.microseconds: 50
jet.idle.noncooperative.max.microseconds: 1000
You can also configure the Jet engine before starting as follows:
JAVA_OPTS=-D<property>=<value> bin/hz-start
The full list of Jet-specific properties can be found inside the
com.hazelcast.jet.core.JetProperties
class and the rest of properties
are located inside com.hazelcast.spi.properties.ClusterProperty
class.
The most important properties are listed here:
Option | Default | Description |
---|---|---|
|
271 |
Total number of partitions in the cluster. |
|
jdk |
What logger should be used by Jet. Valid options are |
|
25 |
The minimum time in microseconds the cooperative worker threads will sleep if none of the tasklets made any progress. Lower values increase idle CPU usage but may result in decreased latency. Higher values will increase latency and very high values (>10000µs) will also limit throughput. |
|
500 |
The maximum time in microseconds the cooperative worker threads will sleep if none of the tasklets made any progress. Lower values increase idle CPU usage but may result in decreased latency. Higher values will increase latency and very high values (>10000µs) will also limit throughput. |
|
25 |
The minimum time in microseconds the non-cooperative worker threads will sleep if none of the tasklets made any progress. Lower values increase idle CPU usage but may result in decreased latency. Higher values will increase latency and very high values (>10000µs) will also limit throughput. |
|
5000 |
The maximum time in microseconds the non-cooperative worker threads will sleep if none of the tasklets made any progress. Lower values increase idle CPU usage but may result in decreased latency. Higher values will increase latency and very high values (>10000µs) will also limit throughput. |
|
1000 |
Maximum number of job results to keep in the cluster, the oldest results will be automatically deleted after this size is reached. |
|
604800 |
Maximum number of time in seconds the job results will be kept in the cluster. They will be automatically deleted after this period is reached. |
Job-specific Configuration
Each job has job-specific configuration options. These are covered in detail in Configuring Jobs.
Client Configuration
When using a Hazelcast client to access Jet engine services, the easiest way to start configuring it using the programmatic approach is as follows:
ClientConfig config = new ClientConfig();
config.getNetworkConfig().addAddress("server1", "server2:5702");
HazelcastInstance client = HazelcastClient.newHazelcastClient(config);
JetService jetFromClient = client.getJet();
Alternatively, you can add hazelcast-client.yaml/xml
to the classpath or
working directory which will be picked up automatically. The location of
the file can also be given using the hazelcast.client.config
system
property; that is, -Dhazelcast.client.config=C:/myhazelcast-client.yaml/xml
.
A sample client YAML file is given below:
hazelcast-client:
# Name of the cluster to connect to. Must match the name configured on the
# cluster members.
cluster-name: myjet
network:
# List of addresses for the client to try to connect to. All members of
# a Hazelcast cluster accept client connections.
cluster-members:
- server1:5701
- server2:5701
connection-strategy:
connection-retry:
# how long the client should keep trying connecting to the server
cluster-connect-timeout-millis: 3000