Doc update for slow operation detector [CTT-1152]#2173
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celenmelike
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JamesHazelcast
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May 5, 2026
| operation details, start time and duration of each slow invocation. All collected data is available in | ||
| the xref:{page-latest-supported-mc}@management-center:monitor-imdg:monitor-members.adoc[Management Center]. | ||
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| The `SlowOperationDetector` is designed to detect relatively long-running operations. Due to its internal scanning mechanism, it cannot reliably detect operations around or below ~1 second (1000 ms). Even if you configure a threshold lower than 1000 ms, such operation cannot be detected. If you need to detect operations that take less than 1 second, you should use a JVM profiler. However, use of third-party profiling tools is at your own risk. We do not provide support or warranties for any external profiler tools. |
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| The `SlowOperationDetector` is designed to detect relatively long-running operations. Due to its internal scanning mechanism, it cannot reliably detect operations around or below ~1 second (1000 ms). Even if you configure a threshold lower than 1000 ms, such operation cannot be detected. If you need to detect operations that take less than 1 second, you should use a JVM profiler. However, use of third-party profiling tools is at your own risk. We do not provide support or warranties for any external profiler tools. | |
| The `SlowOperationDetector` is designed to detect relatively long-running operations. Operations are checked every 1,000ms, and due to this scanning mechanism, it cannot reliably detect operations taking less than 1 second (1,000ms). If the slow operation threshold is configured lower than 1,000ms, it may miss operations if they are not running at the time of each scan. If you need to detect operations that take less than 1 second, you should use a JVM profiler. However, use of third-party profiling tools are done at your own risk and should not be used in production environments. |
| include::clusters:partial$ucn-migrate-tip.adoc[] | ||
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| The defaults catch extremely slow operations but you should set this much lower, say to 1ms, at development time to catch entry processors that could be problematic in production. These are good candidates for our optimizations. | ||
| The defaults catch extremely slow operations, but you can set this lower at development time to catch entry processors that could be problematic in production. However, operations with very short execution times (lower than ~1 second) may not always be detected. Entry processors that are detected as slow are good candidates for our optimizations. |
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I wonder if we should keep this in the docs at all or just remove it? The slow operation detector is not useful for this case imo
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interesting that we had this recommendation before ("you should set this much lower"). It might still make sense in dev, but we should strongly emphasise the randomness of detection and lack of guarantee of reporting all offending operations. In dev as a safety net it is fine, for production or metrics definitely not.
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updated here: 5c851dd. Is it ok for you to keep it like that?
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| |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. | ||
| The value should be set at least 1000 ms for reliable results. The detector cannot detect operations under 1000 ms. |
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This is not quite accurate - it can detect operations under this, it's just a gamble as to whether they are present at the time of captures being made (making results unreliable)
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| The value should be set at least 1000 ms for reliable results. The detector cannot detect operations under 1000 ms. | |
| The value should be set at least 1000 ms. The detector cannot reliably detect all operations taking under 1000 ms. |
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k-jamroz
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May 7, 2026
k-jamroz
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May 12, 2026
| @@ -150,7 +150,7 @@ We have a slow user code detector which can be used to log a warning controlled | |||
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| include::clusters:partial$ucn-migrate-tip.adoc[] | |||
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not really related, but UCD deprecation warning feels misplaced in the middle of slow operation detector description
k-jamroz
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May 12, 2026
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LGTM. Discussion about profilers is more general
JamesHazelcast
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May 13, 2026
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Clarify that operations around or below 1 second cannot be reliably detected by
SlowOperationDetector.Add recommendation to use a JVM profiler for shorter operations.