This is probably a rather peculiar question. I am using Spring Boot 2.0.2 with the default Tomcat container. In order to set up a test in our QA environment that simulates many servers, I would like to set up a Spring Boot-based REST service that listens on a very large number of ports simultaneously. I'm able to do this using the technique previously described in in another SO post (Configure Spring Boot with two ports) which basically adds connectors using TomcatServletWebServerFactory.addAdditionalTomcatConnectors().
The difficulty is that a large number of threads seem to be created for each additional port activated; some empirical measurements show the total to be 17 + (15 * number of ports). This means listening on 250 ports result in 3767 threads created and 500 ports result in 7517 threads created and I would like to go somewhat beyond that number. The test program used to take the above measurements is the bare minimum to bring up a Spring service and there is no code that creates threads explicitly so insofar, as I know, all of those threads were created by Spring/Tomcat.
Is there a way to accomplish this using Spring that doesn't use so many threads per active port? Would an alternate container like Jetty be more efficient?
You can configure the embedded tomcat container properties in spring boot configuration file and set the appropriate numbers for these properties to limit the threads created by Tomcat container -
server.tomcat.max-threads=200 # Maximum amount of worker threads.
server.tomcat.min-spare-threads=10 # Minimum amount of worker threads.
Related
I have developed a microservice using Spring Boot and deployed it as a docker container and when doing performance testing the service I see that the maximum number of threads that created to the service is 20 at any point in time even though the number of calls made is much higher. I have even set the max thread to 4000 and also set Max connection to 10000 along with all db configuration and server has 24 core and 64 gb ram still no improvement Are there any limitations with respect to number of calls that can be made to a microservice developed using Spring Boot or is the issue is with docker container? Or is this normal?
Is it possible to handle actuator requests like health within a separate thread pool from the "main" application?
Why am I asking?
I've got an application that might sometimes use up all available threads, and the Kubernetes health check is failing due to the unavailability of a thread to compute the health endpoint request.
I want to make sure that every health request is processed no matter how much load the application is under.
I was thinking about maybe defining a separate thread pool for the actuators to operate with, but I am not sure how to do this.
We had a similar problem with some of our apps when running in Kubernetes. We looked at different ways of creating multiple tomcat connectors and changing the spring management port to get the desired affect, but never quite got it.
In the end, we attacked the root of the problem, which was resource starvation within the pod. We found that the apps experiencing the health check timeouts had lots of extra threads for various 3rd party thread pools. In some cases we had apps with close to 500 threads, so even under what we considered moderate load, the tomcat pools would get starved and couldn't handle new requests.
FWIW, the biggest culprit we found was the effect of CPU request on a pod and the JDK. When we didn't set any request, the JDK would see every CPU on the node when it queried for numbers of processors. We found there are lots of places in the Java ecosystem where number of processors is used to initialize different thread pools.
In our case, each node had 36 processors, and we found around 10-12 thread pools using this number to determine size...not hard to see to how an app could quickly grow to 500 threads.
I believe that switching to the nonblocking stack (Webflux) could solve your issue, should this be an option for you. If you rely on some blocking API (e.g. JDBC) you can publish it on a separate thread pool (e.g. Schedulers.elastic()). Thus, the HTTP request threads should always be available for processing the incoming trafic (including health check) and the long-running, blocking operations would be processed in a dedicated thread pool. I believe that similar effect should be possible using the asynchronous servlets API or anything that builds on top of it.
If you are using Spring Boot >= 2.2, you can use the separate library spring-boot-async-health-indicator to run your healthchecks on a separate thread pool.
Simply annotate your HealthIndicator with #AsyncHealth:
#AsyncHealth
#Component
public class AsynchronousHealthCheck implements HealthIndicator {
#Override
public Health health() { //will be executed on a separate thread pool
actualCheck();
return Health.up().build();
}
}
Disclaimer: I created this library for this exact purpose
I am having multiple spring boot applications which are connected to kafka (clustrized with 3 brokers)and also i integrated transaction synchronization (chainedKafkaTransactionManager). so i want to know should i give the same TransactionIdPrefix value in kafka config for all the multiple application or diffrent one.
i tried giving a random generated TransactionIdPrefix for each application. but i think in some time in multi thread environment in Listeners method it will take old data from database (jpa repositories)
is it problem because of diffrent TransactionIdPrefix ?
It depends; if they are multiple instances of the same app and the transactions are started by consumers, the prefix must be the same, so that zombie fencing is handled properly when partitions move from one instance to another after a rebalance.
If the transactions are started by producers, the prefix must be unique in each instance.
If they are different applications they should have different prefixes, regardless of what starts the transaction.
I am using spring boot 2.0.4.RELEASE. My doubt is whether my application is running in event loop style or not. I am using tomcat as my server.
I am running some performance tests in my application and after a certain time I see a strange behaviour. After the request reaches 500 req/second , my application is not able to serve more than 500 req/second. Via prometheus I was able to figure out max thread for tomcat were 200 by default. Looks like all the threads were consumed and that's why , it was not able to server more than 500 req/second. Please correct me if am wrong.
Can the tomcat server run in event-loop style ?
How can I change the event-loop size for tomcat server if possible.
Tried changing it to jetty still the same issue. Wondering if my application is running in event loop style.
Hey i think that you are doing something wrong in your project maybe one of your dependency does not support reactive programming. If you want to benefit from async programing(reactive) your code must be 100 reactive even for security you must use reactive spring security.
Normally a reactive spring application will run on netty not in tomcat so check your dependency because tomcat is not reactive
This is more of a analysis. After running some performance test on my local machine , I was able to figure out what was actually happening inside my application.
What I did was, ran performance test on my local machine and analysed the application through JConsole.
As I said I scheduled all my blocking dB calls to schedulers.elastic. What I realised that I it is causing the bottleneck. since my dB connections are limited and I am using hikari for connection pooling so it doesn’t matter the number of threads I create out of elastic pool.
Since reactive programming is more about consuming resource to the fullest with lesser number of threads, since the threads were being created in unbounded way so it was no different from normal application .
So what I did as part of resolution limited the number of threads to 100 that were supposed to be used by for dB calls. And bang number jumped from 500 tps to 2300 tps.
I know this is not the number which one should expect out of reactive application , it has much more capability. Since right now I do not have any choice but to bear with non reactive drivers .Waiting for production grade availability of reactive drivers for mssql server.
I have read this post but it's not my case and not enough clear:
How does load balancing in Spring XD get done?
I have a composed job with different instances of the same sub-jobs deployed in different containers. My composed job is scheduled to run periodically. I need to know how Spring XD choose the sub-jobs instances to invoke for every new request to the composed job.
The same question for a stream triggered every X minutes.
It's handled by the transport (rabbit, redis).
Each downstream module competes for messages - with rabbit it will generally be round robin; with redis it will be more random.