Log trace error using TraceCallable, TraceRunnable in ExecutorService about spring-cloud-sleuth HOT 1 CLOSED

I will explain the whole problem. I was evaluating the Spring cloud sleuth for tracing. There was no direct support for executors but there were two classes TraceCallable and TraceRunnable in Sleuth which supports tracing. I wrote one ExecutorService to wrap Runnable and Callable to their respective Traceable implementations. I created one instance of that ExecutorService(FixedThreadPool with 3 threads as its size. The size here doesn't matter).
The app I created is Spring Boot app which accepts request from UI(browser), sends it to Service layer to cater that request(Service layer uses Executor). I was sending multiple requests to test the feasibility of support for Executors. Then I found the weird Htrace error. Earlier I thought the issue might be because in worker Thread, span is not removed from their thread local variable. This is still true. But when I wrote unit test case to support my hypothesis, I found everything is working fine. The code for unit test case is :

@Test
public void test_whenTraceContextOfWorkerThreadIsNotClosed_thenException() {

    final AtomicInteger counter = new AtomicInteger(0);
    final CountDownLatch latch = new CountDownLatch(TOTAL_THREADS);
    TraceScope scope = this.trace.startSpan("PARENT");

    for (int i = 0; i < TOTAL_THREADS; i++) {
        traceableExecutorService.execute(new MyRunnable(counter, latch));
    }

    try {
        latch.await();
    } catch (InterruptedException e) {
        e.printStackTrace();
    }

    scope.close();

    verify(this.publisher, times(NUM_SPANS)).publishEvent(isA(SpanAcquiredEvent.class));
    verify(publisher, times(NUM_SPANS)).publishEvent(isA(SpanReleasedEvent.class));

    ArgumentCaptor<ApplicationEvent> captor = ArgumentCaptor
            .forClass(ApplicationEvent.class);
    verify(publisher, atLeast(NUM_SPANS)).publishEvent(captor.capture());

    List<Span> spans = new ArrayList<>();
    for (ApplicationEvent event : captor.getAllValues()) {
        if (event instanceof SpanReleasedEvent) {
            spans.add(((SpanReleasedEvent) event).getSpan());
        }
    }

    assertThat("spans was wrong size", spans.size(), is(NUM_SPANS));
}

After giving it a think, I found that in close() of TraceScope class, last line is TraceContextHolder.setCurrentSpan(this.savedSpan);

When I printed on console this saved span, it was the parent span when these TraceCallable or TraceRunnable were created.

Now the scenerio is, In web-based application and when we are sharing that executorService and when multiple requests are coming in TraceFilter starts or continue the span. For two different requests, the parent span will be different and if in the executorService same thread tries to execute task, it will throws weird Htrace error. I hope I explained the problem in detail.

from spring-cloud-sleuth.