Logstash hangs with error sized_queue_timeout

Cross-posting this from stackoverflow.

We have a logstash pipeline in which numerous logstash-forwarders forward logs to a single logstash instance. Many times we have observed that the logstash hangs with the below error:-

[2016-07-22 03:01:12.619]  WARN -- Concurrent::Condition: [DEPRECATED] Will be replaced with Synchronization::Object in v1.0.
called on: /opt/logstash-1.5.3/vendor/bundle/jruby/1.9/gems/logstash-input-lumberjack-1.0.2/lib/logstash/sized_queue_timeout.rb:16:in `initialize'
Exception in thread ">output" java.lang.UnsupportedOperationException
        at java.lang.Thread.stop(Thread.java:869)
        at org.jruby.RubyThread.exceptionRaised(RubyThread.java:1221)
        at org.jruby.internal.runtime.RubyRunnable.run(RubyRunnable.java:112)
        at java.lang.Thread.run(Thread.java:745)

Our logstash config looks like below:-

input {
 lumberjack {
  port => 6782
  codec => json {}
  ssl_certificate => "/opt/logstash-1.5.3/cert/logstash-forwarder.crt"
  ssl_key => "/opt/logstash-1.5.3/cert/logstash-forwarder.key"
  type => "lumberjack"

filter {
  if [env] != "prod" and [env] != "common" {
    drop {}
  if [message] =~ /^\s*$/ {
    drop { }

output {
  if "_jsonparsefailure" in [tags] {
    file {
      path => "/var/log/shop/parse_error/%{env}/%{app}/%{app}_%{host}_%{+YYYY-MM-dd}.log"
  } else {
    kafka {
      broker_list => ["kafka:9092"]
      topic_id => "logstash_logs2"

On restarting the logstash it starts working again. Can some one let me know why this problem comes and how can we get around this without restarting logstash everytime?

What version of things are you running?

Also, please note the LSF is deprecated and will be totally unsupported soon.

Logstash 1.5.3
Kafka 0.8.
ES - 1.7.1

My pipeline looks like below:-

Multiple LF --- Logstash Collector --- Kafka---- Logstash Indexer --- ES

I am seeing the problem in logstash-collector.

Just to add in preparation for moving to beats I tried upgrading to
logstash 2.3.4. But that started giving some other issue:-

So at this point I am stuck with LSF.