Ramesh,
On 4/28/25 7:00 AM, Ramesh B R wrote:
The application hosted on tomcat9 exposes soap api which is consumed by SAP.
On a daily basis we are getting 200 thousands transactions and out of that
we could see around 1000 to 2000 failed transactions due to CONNECTION
REFUSED, CONNECTION CLOSED and PARSE ERROR.
Are these errors being recorded by the client or the server?
The application is running on 6 VM's and each VM had 12 CPU and 36 GB RAM
Any suggestions to avoid these failures.
PARSE ERROR ought to be easy to track down and isn't really in-scope for
a Tomcat mailing list question.
CONNECTION REFUSED and CONNECTION CLOSED are more on-topic.
What does CONNECTION CLOSED mean? Every connection closes eventually, so
is this ... an expected connection-closure event? Before your servlet
response is sent? Before the request is sent but after the connection is
made?
CONNECTION REFUSED is likely due to one of the following:
1. Service is coming up/down - can you confirm there are no restarts
occurring during your data sampling?
2. TCP/IP backlog is full on the target server, this is normal.
For the backlog issue, you should do a bit of simple maths.
You have 6 VMs running Tomcat. How many instances of Tomcat is that? 6?
Do you have any thing like a load-balancer, reverse-proxy, etc. out in
front of those 6 (?) Tomcats? How many connections is Tomcat configured
to handle? Are you reaching that connection limit? What is the TCP/IP
backlog being set to from your Tomcat configuration? Is the OS actually
respecting that backlog configuration? (The OS is under no obligation to
actually give you exactly what you requested.)
-chris
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