يا له من طرف ثالث .jar كان يستعد لنا ...

سأخبرك عن حادثة مسلية واحدة جعلت فريقنا بأكمله يتعرق كثيرًا ، وكاد يتسبب في انهيار عصبي للبعض. نتج عن البحث أداة فعالة يمكن لأي مطور استخدامها لإثارة أعصاب بقية الفريق. الهدف من هذا المنشور هو التحذير من المواقف غير التافهة والاستعداد لها.

استطرادا غنائي

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

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

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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 — . , :

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• لا تتوقع إصلاح تذكرتك بسرعة أو قبول طلب سحب سريعًا - سيستغرق الأمر عدة أشهر إلى عدة سنوات قبل نشر الإصلاح في المستودع الرسمي.
• إذا كنت تستخدم Logback ، فكيِّف الاستثناء بإزالة المراجع الدائرية قبل تسجيله. يمكن القيام بذلك فقط في معالجات المستوى الأعلى في Thread و ExecutorService.