Essential Linux Commands and Java Debugging Tools for Backend Engineers

The author, a senior architect, shares a curated list of Linux commands and Java debugging tools that are valuable for troubleshooting backend systems.

Linux Command Utilities

Commonly used commands such as tail -300f shopbase.log, various grep patterns, awk scripts, and find options are presented with examples for log inspection, file searching, and directory queries.

System Monitoring Tools

Tools like tsar for historical and real‑time metric collection, and top for process monitoring are demonstrated with command snippets and screenshots.

Java Debugging and Profiling

Several Java‑specific utilities are introduced:

btrace : bytecode injection for tracing method calls and monitoring ArrayList usage.

Greys : class inspection, method tracing, and performance analysis.

Arthas : Alibaba’s open‑source troubleshooting tool.

JProfiler : commercial profiler for deep analysis.

eclipse MAT and zprofiler : heap dump analysis tools.

Sample btrace script:

@OnMethod(clazz = "java.util.ArrayList", method="add", location = @Location(value = Kind.CALL, clazz = "/.*/", method = "/.*/"))
public static void m(@ProbeClassName String probeClass, @ProbeMethodName String probeMethod, @TargetInstance Object instance, @TargetMethodOrField String method) {
    if(getInt(field("java.util.ArrayList", "size"), instance) > 479){
        println("check who ArrayList.add method:" + probeClass + "#" + probeMethod + ", method:" + method + ", size:" + getInt(field("java.util.ArrayList", "size"), instance));
        jstack();
        println();
        println("===========================");
        println();
    }
}

JVM Command Line Tools

Essential commands such as jps, jstack, jinfo, jmap, jstat, and jdb are listed with typical usage examples for process listing, stack tracing, heap inspection, and remote debugging.

Additional Utilities

Tips on using dmesg to detect OOM killer events, VM options for class loading tracing, and methods for resolving jar conflicts (e.g., mvn dependency:tree, -XX:+TraceClassLoading, Greys sc) are also provided.

Overall, the article serves as a handy reference for backend engineers to efficiently diagnose, monitor, and troubleshoot Java applications in production.