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Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
System process daemons that are system-wide provided by mac os x are described by launchd preference files that can be showed with the command:
$ sudo ls -all /System/Library/LaunchDaemons/
Third party process daemons that are system-wide provided by the administrator are described by preference files that can be showed with the command:
$ sudo ls -all /Library/LaunchDaemons/
Launch Agents that are per-user provided by mac os x usually loaded when the user logs in. Those provided by the system can be found with:
$ sudo ls -all /System/Library/LaunchAgents/
Launch Agents that are per-user provided by the administrator and usually loaded when the user logs in. Those provided by the system can be found with:
Flame graphs are a nifty debugging tool to determine where CPU time is being spent. Using the Java Flight recorder, you can do this for Java processes without adding significant runtime overhead.
When are flame graphs useful?
Shivaram Venkataraman and I have found these flame recordings to be useful for diagnosing coarse-grained performance problems. We started using them at the suggestion of Josh Rosen, who quickly made one for the Spark scheduler when we were talking to him about why the scheduler caps out at a throughput of a few thousand tasks per second. Josh generated a graph similar to the one below, which illustrates that a significant amount of time is spent in serialization (if you click in the top right hand corner and search for "serialize", you can see that 78.6% of the sampled CPU time was spent in serialization). We used this insight to spee
Use jq to profile the schema of a given JSON object or an array of JSONs objects
Profile JSON schema
Using jq is great for examining JSON objects. You can extend its functionality with custom methods. The following is useful to understand at a high level the structure of arbitrary JSONs which is useful when trying to understand new data sources.