Apache connection pool instrumentation #457
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| assertThat(client.getNumRoutes()).describedAs("routes").isEqualTo(1); | ||
| assertThat(client.getPoolStats().getAvailable()) | ||
| .describedAs("available") | ||
| .isEqualTo(0); |
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I think graphing the number available will be kinda interesting, as this should tell us how quickly we could handle bursts of traffic
/**
* Gets the number idle persistent connections.
* <p>
* The total number of connections in the pool is equal to {@code available} plus {@code leased}.
* </p>
*
* @return number idle persistent connections.
*/
public int getAvailable() {
| PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager( | ||
| RegistryBuilder.<ConnectionSocketFactory>create() | ||
| .register("http", PlainConnectionSocketFactory.getSocketFactory()) | ||
| .register("https", sslSocketFactory) |
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I wonder if we can wrap these to add a meter of connection rate, and wrap the pool manager to capture the rate connections requested?
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Mmm that would be cool, so dividing one by the other tells us how effectively we're re-using... Do we not already get that connection rate from the tritium tls.handshakes?
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Tritium handshake instrumentation would work assuming https, but I don’t think we wire it up yet.
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Closing in favour of #498 |
Before this PR
We have hypotheses that connection re-use has a big impact on our most performance-sensitive services like timelock. Currently, we just use the tls.handshake graphs to
After this PR
==COMMIT_MSG==
Each closeable apache client now exposes methods which reveal statistics about the connection pool.
==COMMIT_MSG==
After merging, we'll have to carefully wire these up to gauges in witchcraft, ensuring that we don't prevent objects from being GC'd just by having a reference in a tritium registry somewhere.
Possible downsides?