Clever Geek Handbook

Lo que .jar nos estaba preparando ...

Les contaré un incidente divertido que hizo sudar mucho a todo nuestro equipo y casi provocó un ataque de nervios en algunos. La investigación ha dado como resultado una herramienta eficaz que cualquier desarrollador puede utilizar para poner nervioso al resto del equipo. El objetivo de este post es advertir sobre posibles situaciones no triviales y estar preparado para ellas.





Digresión lírica



, . 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 — . , :



  • , , , . .
  • , , .
  • , .
  • , .
  • No espere que su ticket se solucione rápidamente o que se acepte rápidamente una solicitud de extracción; pasarán varios meses o varios años antes de que la corrección se publique en el repositorio oficial.
  • Si está utilizando Logback, adapte la excepción eliminando las referencias circulares antes de registrarla. Esto solo se puede hacer en los controladores de nivel superior en Thread y ExecutorService.


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