Clever Geek Handbook

第三方.jar为我们准备了什么...

我将告诉您有关一个有趣的事件，该事件使我们的整个团队都汗流，背，几乎使一些人崩溃了。研究产生了一种有效的工具，任何开发人员都可以使用它来吸引团队的其他成员。这篇文章的目的是警告可能的非平凡情况，并为它们做好准备。





抒情离题



, . open-source , - , , , . , . , . . , . , work-around, , .



:



  • . , .
  • . , , . , , , StackOverflow.
  • , , .
  • . , . : , “ ” .
  • . , .


.





, . , , SFTP .



:



public class Task implements Runnable {
    static final Logger log = LoggerFactory.getLogger(Task.class);

    public void run() {
        log.info("Task started");
        try(var remoteFile = createRemoteFile(xxx)) {
            this.setState(STARTED);
            for (int page = 0;;page++) {
                var block = service.requestDataBlock(page);
                if (block == null) break;
                transformData(block);
                remoteFile.writeDataBlock(block);
            }
            this.setState(FINISHED);
            log.info("Task finished");
        } catch (Exception ex) {
            log.error("Task failed", ex);
            this.setState(ERROR);
        }
    }
}


, , state=STARTED . — - . "Task started", "Task finished" "Task failed".



1



, , . — - dead lock. , thread dump , . .



2



, thread dump, , — . - "Task started", "Task finished" "Task failed"! , , Throwable Error, Exception. catch(Exception) catch(Throwable) . — , thread dump- .



3



, . , , thread dump, , . - . , . !



4



— , — , . , - OutOfMemoryError, catch ( OutOfMemoryError). java -XX:+CrashOnOutOfMemoryError -XX:+HeapDumpOnOutOfMemoryError. java- OutOfMemory hs_err_pid, — memory dump . : OutOfMemory — ( ), , .



5



. : , ! - Thread.stop(), , - JDK. — , , - , . System.out.println(), try-catch . :



java.lang.StackOverflowError
    at java.lang.reflect.InvocationTargetException.<init>(InvocationTargetException.java:72)
    at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at ch.qos.logback.classic.spi.ThrowableProxy.<init>(ThrowableProxy.java:66)
    at ch.qos.logback.classic.spi.ThrowableProxy.<init>(ThrowableProxy.java:72)
    at ch.qos.logback.classic.spi.ThrowableProxy.<init>(ThrowableProxy.java:72)
    at ch.qos.logback.classic.spi.ThrowableProxy.<init>(ThrowableProxy.java:72)
    at ch.qos.logback.classic.spi.ThrowableProxy.<init>(ThrowableProxy.java:72)
    at ch.qos.logback.classic.spi.ThrowableProxy.<init>(ThrowableProxy.java:72)
            ...


! , Logback. , , — Error, ! , :



log.error("Task failed", ex);




What a Terrible Failure (WTF?!)



- ? ThrowableProxy Logback , suppressed exceptions, :



suppressed = new ThrowableProxy[throwableSuppressed.length];
for (int i = 0; i < throwableSuppressed.length; i++) {
   this.suppressed[i] = new ThrowableProxy(throwableSuppressed[i]);
   this.suppressed[i].commonFrames = 
        ThrowableProxyUtil.findNumberOfCommonFrames(throwableSuppressed[i].getStackTrace(),
                   stackTraceElementProxyArray);
}


, suppressed exceptions . :



@Test
public void testLogback() throws Exception {
    Logger log = LoggerFactory.getLogger(TestLogback.class);
    //    java 
    // java.lang.IllegalArgumentException: Self-suppression not permitted
    //ex.addSuppressed(ex);
    //   
    Exception ex = new Exception("Test exception");
    Exception ex1 = new Exception("Test exception1");
    ex.addSuppressed(ex1);
    ex1.addSuppressed(ex);
    log.error("Exception", ex);
}


— StackOverflowError! Java, ( 19000 maven-) , , . Logback , SFTP — Apache VFS. IOException suppressed, IOException. .



Logback ? , 2014 :

https://jira.qos.ch/browse/LOGBACK-1027

2019:

https://jira.qos.ch/browse/LOGBACK-1454

.



, Java ? , ex.printStackTrace(), , CIRCULAR REFERENCE:



java.io.IOException: Test exception
    at org.example.test.TestLogback.lambda$testJavaOutput$1(TestLogback.java:43)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)
    Suppressed: java.lang.Exception: Test exception1
        at org.example.test.TestLogback.lambda$testJavaOutput$1(TestLogback.java:44)
        ... 5 more
    [CIRCULAR REFERENCE:java.lang.Exception: Test exception]


java.util.logging.



Log4j , suppressed exception.



14:15:22.154 [main] ERROR org.example.test.TestLogback - Test
java.lang.Exception: Test exception
    at org.example.test.TestLogback.testLog4j(TestLogback.java:61) [test-classes/:?]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_251]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_251]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_251]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_251]
    Suppressed: java.lang.Exception: Test exception1
        at org.example.test.TestLogback.testLog4j(TestLogback.java:62) [test-classes/:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_251]
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_251]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_251]
        at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_251]
        Suppressed: java.lang.Exception: Test exception
            at org.example.test.TestLogback.testLog4j(TestLogback.java:61) [test-classes/:?]
            at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_251]
            at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_251]
            at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_251]
            at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_251]




Logback — . , :



  • , , , . .
  • , , .
  • , .
  • , .
  • 不要期望您的票证会被快速修复或快速接受拉取请求-修复程序要花费数月至数年才能在官方存储库中发布。
  • 如果使用的是Logback，请通过在记录日志之前删除循环引用来适应该异常。这只能在Thread和ExecutorService中的顶级处理程序中完成。


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