subprojects/parseq-tracevis-server/src/main/java/com/linkedin/parseq/GraphvizEngine.java
private Task<Exec.Result> getBuildTask(final String hash, final InputStream body) {
    Task<Exec.Result> existing = _inFlightBuildTasks.get(hash);
    if (existing != null) {
      LOG.info("using in flight shareable: " + hash);
      return existing.shareable();
    } else {
      Task<Exec.Result> newBuildTask = createNewBuildTask(hash, body);
      existing = _inFlightBuildTasks.putIfAbsent(hash, newBuildTask);
      if (existing != null) {
        LOG.info("using in flight shareable: " + hash);
        return existing.shareable();
      } else {
        return newBuildTask;
      }
    }
  }
private Task<Exec.Result> getBuildTask(final String hash, final InputStream body) {
    Task<Exec.Result> existing = _inFlightBuildTasks.get(hash);
    if (existing != null) {
      LOG.info("using in flight shareable: " + hash);
      return existing.shareable();
    } else {
      Task<Exec.Result> newBuildTask = createNewBuildTask(hash, body);
      existing = _inFlightBuildTasks.putIfAbsent(hash, newBuildTask);
      if (existing != null) {
        LOG.info("using in flight shareable: " + hash);
        return existing.shareable();
      } else {
        return newBuildTask;
      }
    }
  }
Returns task that builds graph using graphviz. Returned task might be shared with other concurrent requests.