Lumberjack java.nio.BufferOverflowException

Hi.

Sometime my logstash crash and I have this error in logstash.err :
http://pastebin.com/evNHP4J5

And this in logstash.log :

http://pastebin.com/pryieXdF

It seems to be a problem of memory.
I increased the LS_HEAP_SIZE to 2g but it doesn't solve the problem.

Here is my config :

input {
lumberjack {
port => 5000
type => "logs"
ssl_certificate => "/etc/logstash/mycrt.crt"
ssl_key => "/etc/logstash/mykey.key"
codec => json {
charset => "Windows-1252"
}
}
lumberjack {
port => 5001
type => "logs"
ssl_certificate => "/etc/logstash/mycrt.crt"
ssl_key => "/etc/logstash/mykey.key"
codec => plain {
charset => "Windows-1252"
}
}
}
output {
if "_grokparsefailure" in [tags] or "_dateparsefailure" in [tags] {
file {
path => "/var/log/logstash/parsefailure.log"
}
}
elasticsearch {
hosts => ["myhost:9200"]
sniffing => true
manage_template => false
index => "logstash-%{+YYYY.MM.dd}"
}
stdout {
codec => rubydebug
}
}

What can I do to solve this problem ?