How to improve problem solving skills
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This document provides tips on improving problem solving skills. It discusses why problem solving skills are important for daily work and responsibilities. Some key tips include understanding the problem fully before searching online, checking logs and error messages, reproducing the problem locally, considering different angles to solve it, asking others for help, and practicing common problem types. Tools like Eclipse, log files, source control and debuggers can help pinpoint issues. It's important to learn from problems by preventing recurrences.
How to improve problem solving skills
- 1. How to Improve Problem Solving Skills - JefferyYuan
- 2. Disclaimer Just try to summarize what I have learned.
- 3. Why Problem-solving skills matters Problem Solving and troubleshooting »Is fun »Is part of daily work »Make us solve problem • More efficiently • With more confidence • Less pressure • Go home earlier
- 4. Why Problem-solving skills matters »Solve the problem when needed • no matter whether its not related with you • It’s your responsibility if it blocks your or the team’s work
- 5. Understand the problem/environment first Understand the problem before google search otherwise it may just lead you to totally wrong directions. Find related log/data Copy logs/info that maybe related
- 6. Check the Log and Error Message Read/Understand the error message Where to find log Common places: /var/log From command line: -Dcassandra.logdir=/var/log/cassandra
- 7. Case Study – The Log and Error Message Problem: Failed to talk Cassandra server: 10.10.10.10 - Where 10.10.10.10 comes from? gfind . -iname '*.jar' -printf "unzip -c %p | grep -q 10.10.10.10' && echo %pn" | sh -It comes from commons2, what’s the current settings in Github -Now the problem and solution is clear: Just upgrade commons2 to latest version
- 8. Source code is always the ultimate truth Find related code in Github Find examples/working code Understand how/why the code works by running and debug the code Check the log with the code - Most problems can be solved by checking log and source code
- 9. Reproduce the problem Find easier way to reproduce them - main method, unit test, mock Simplify the suspect code - Find the code related, remove things not realtedUse Reproduce locally Connect to the remote data in local dev Remote debug - Last resort, slow
- 10. Solving Problem from Different Angles Sometime we find problem in production and we need code change to fix it -Try to find whether we can fix a workaround by changing database/Solr or other configuration -We can fix code later
- 11. Find Information Effectively Google search: error message, exception Search source code in Github/Eclipse Search log Search in IDE -- Cmd+alt+h, cmd+h Search command history -- history | grep git | grep erase -- history | grep ssh | grep 9042 Know company’s internal resource – where to find them Know some experts (in company) you can ask help from
- 12. Ask for help From coworkers Stackoverflow Specific forums http://lucene.472066.n3.nabble.com/Solr-f472067.html - Provide context and info you find - Ask help for same/similar things once, then you know how to do it - Learn the knowledge itself - But also learn their thinking process
- 13. Fix same/similar/related problems in other places We make mistakes in one place It's very likely we make same/similar/related in other places GetMapping(value = "/config/{name:.+}")
- 14. Knowledge Be prepared Know what problem may happen, the difference etc Know the services/libraries you are using Apache/Tomcat configuration How to manage/troubleshoot Cassandra/Kafka/Solr
- 15. Knowledge Practice - Redis cache.put Hangs - Get threaddump, figure out what is happening when read from cache - Read related code to figure out how Spring implements @Cacheable(sync=true) RedisCache$RedisCachePutCallback - Check whether there is cacheName~lock in redis When use some feature, know how it's implemented.
- 16. Knowledge Common Problems – More to add in future Different versions of same library - mvn dependency:tree - mvn dependency:tree -Dverbose -Dincludes=com.amazonaws:aws-java-sdk-core
- 17. Practice - Iterator vs Iterable What’s the problem in the following Code? @Cacheable(key = "#appName") public Iterator<Message> findActiveMessages(final String appName) {}
- 18. Practice - Iterator vs Iterable How we find the root cause - Symptoms: The function only works once in a while: when cache is refreshed - Difference between Iterator vs Iterable - Don't use Iterator when need traverse multiple times - Don't use Iterator as cache value
- 19. Practice 2 - Spring @Cacheable Not Working The class using cache annotation inited too early - Add a breakpoint at the default constructor of the bean, then from the stack trace we can figure out why and which bean (or configuration class) causes this bean to be created - Understand how spring cache works internally, spring proxy - CacheAspectSupport
- 20. Building Application to Be Troubleshooting Friendly Debug Feature Return debug info that can check from response without having to check the log - Of course secured, protected Mock User Feature Preview Feature In memory test users in test env
- 21. How to write test efficiently Take time to learn: Hamcrest, Mockito, JUnit, TestNG, REST Assured Add Static Import Preferences > Java > Editor > Content Assist > Favorites, then add: org.hamcrest org.hamcrest.Matchers.* org.hamcrest.CoreMatchers.* org.junit.* org.junit.Assert.* org.junit.Assume.* org.junit.matchers.JUnitMatchers.* org.mockito.Mockito org.mockito.Matchers org.mockito.ArgumentMatchers io.restassured.RestAssured
- 22. Misc. – Part 1 Don't overcomplicate it. - In most cases, the solution/problem is quite simple Troubleshooting is about thinking what may go wrong. Track what change you have made
- 23. Misc. – Part 2 When help others -Ask what related change they have done Ask help from others. -Try to understand the problem and fix it by yourself first. -Provide log or any information that may help others understand the problem. When work on urgent issues with others -Collaborate timely -Let others know what you are testing, what's your progress, what you have found, what you will do next -Listen to others
- 24. Misc. – Part 3 Think More - Think over the code/problem, try to find better solution even it's already fixed Everything that stops you from working effectively is a problem - No access, slack different teams etc Fix them
- 25. Reflection: Lesson Learned How we find the root cause Why it takes so long What we learned What's the root cause Why we made the mistake How we can prevent this happens again Share the knowledge in the team Take time to solve problem, but only (take time to) solve it once
- 26. Tools - Eclipse Use Conditional Breakpoint to Execute Arbitrary Code (and automatically) Use Display View to Execute Arbitrary Code Find which jar containing the class and the application is using - MediaType.class.getProtectionDomain().getCodeSource().getLocation() Breakpoint doesn't work - Multiple versions of same class or library
- 27. Practice - Connect to the remote data in local dev Create a tunnel to zookeeper and solr nodes Add a conditional breakpoint at CloudSolrClient.sendRequest(SolrRequest, String) - before LBHttpSolrClient.Req req = new LBHttpSolrClient.Req(request, theUrlList); theUrlList.clear(); theUrlList.add("http://localhost:18983/solr/searchItems/"); theUrlList.add("http://localhost:28983/solr/searchItems/"); return false;
- 28. Tools - Decompiler CFR http://www.benf.org/other/cfr/ - Best, Support java8 JD-GUI Sometimes, it doesn't work
- 29. Tools - Java jcmd: One JDK Command-Line Tool to Rule Them All jcmd <pid> Thread.print jcmd <pid> GC.heap_dump <filename> Thread dump Analyzer http://fastthread.io/ Heap dump Analyzer Eclipse MAT VisualVM
- 30. Tools - Misc Splunk - After search and find the problem, use nearby Events +/- x seconds to show context nc -zv; lsof; df;find;grep Search Contents of .jar Files for Specific String gfind . -iname '*.jar' -printf "unzip -c %p | grep -q 'string_to_search' && echo %pn" | s Fiddler
- 31. Resource Debug It!: Find, Repair, and Prevent Bugs in Your Code Shameless plug https://www.slideshare.net/lifelongprogrammer http://lifelongprogrammer.blogspot.com/search/label/Problem%20Solving http://lifelongprogrammer.blogspot.com/search/label/Troubleshooting http://lifelongprogrammer.blogspot.com/search/label/Debug