You can configure the Stream
Manager (SM) in a
topology using the parameters below, including how the SM handles back
pressure.
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 |