| --- |
| id: cluster-config-stream |
| title: Stream Manager |
| sidebar_label: Stream Manager |
| --- |
| |
| |
| You can configure the [Stream |
| Manager](heron-architecture#stream-manager) (SM) in a |
| topology using the parameters below, including how the SM handles [back |
| pressure](#back-pressure-parameters). |
| |
| ## Back Pressure Parameters |
| |
| Parameter | Meaning | Default |
| :-------- |:------- |:------- |
| `heron.streammgr.network.backpressure.threshold` | The number of times the SM should wait to see a buffer full while enqueueing data before declaring the start of backpressure | `3` |
| `heron.streammgr.network.backpressure.highwatermark.mb` | The high water mark on the number of megabytes that can be left outstanding on a connection | `50` |
| `heron.streammgr.network.backpressure.lowwatermark.md` | The low water mark on the number of megabytes that can be left outstanding on a connection | `30` |
| `heron.streammgr.network.options.maximum.packet.mb` | The maximum packet size, in megabytes, for the SM's network options | `100` |
| |
| ## Timeout Interval |
| |
| Parameter | Meaning | Default |
| :-------- |:------- |:------- |
| `heron.streammgr.xormgr.rotatingmap.nbuckets` | TODO | `3` |
| |
| ## Other Parameters |
| |
| Parameter | Meaning | Default |
| :-------- |:------- |:------- |
| `heron.streammgr.packet.maximum.size.bytes` | Maximum size (in bytes) of packets sent out from the SM | `102400` |
| `heron.streammgr.cache.drain.frequency.ms` | The frequency (in milliseconds) at which the SM's tuple cache is drained | `10` |
| `heron.streammgr.cache.drain.size.mb` | The size threshold (in megabytes) at which the SM's tuple cache is drained | `100` |
| `heron.streammgr.client.reconnect.interval.sec` | The reconnect interval to other SMs for the SM client (in seconds) | `1` |
| `heron.streammgr.client.reconnect.tmaster.interval.sec` | The reconnect interval to the Topology Master for the SM client (in seconds) | `10` |
| `heron.streammgr.tmaster.heartbeat.interval.sec` | The interval (in seconds) at which a heartbeat is sent to the Topology Master | `10` |
| `heron.streammgr.connection.read.batch.size.mb` | The maximum batch size (in megabytes) at which the SM reads from the socket | `1` |
| `heron.streammgr.connection.write.batch.size.mb` | The maximum batch size (in megabytes) to write by the stream manager to the socket | `1` |
