BlazeDS Polling Interval set to 0: Unwanted side-effects?

tl;dr: Setting the polling-interval to 0 has given my performance a huge boost, but I am worried about possible problems down the line.

In my application, I am doing a fair amount of publishing from our java server to our flex client, publishing on a va开发者_StackOverflow中文版riety of topics and sub-topics.

Recently, we have been on a round of performance improvements system-wide, and the messaging layer was proving to be a big bottleneck.

A few minutes ago, I discovered that setting the <polling-interval-millis> property in our services-config.xml to 0 caused published messages, even when there are lots of them, to be recognized by the client almost instantly, instead of with the 3 second delay that is the default value for polling-interval-millis, which has obviously had a tremendous impact.

So, I'm pretty happy with the current performance, only thing is, I'm a bit nervous about unintended side-effects caused by this change. In particular, I am worried about our Flash client slowing way down, and of way too much unwanted traffic.

My preliminary testing has not borne out this fear, but before I commit the change to our repository, I was hoping that somebody with experience with this stuff would chime in.

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Unfortunately your question is too general...there is no way to receive a specific answer. I'll write below some ideas, maybe they are helpful.

Decreasing the value from 3 to 0 means that you are receiving new data way faster. If your Flex client uses this data in order to make complex computations it is possible to slow your client or to show obsolete data (it is a known pattern, see http://help.adobe.com/en_US/LiveCycleDataServicesES/3.1/Developing/WS3a1a89e415cd1e5d1a8a18fb122bdc0aad5-8000Update.html ). You need to understand how the data is processed and probably to do some client benchmarking.

Also the server will have to handle more requests, and it would be good to identify what is the maximum requests per second which can be handled. For that, you will need to use a tool like Jmeter in order to detect the maximum capacity of your system, after that you can do some computations trying to figure out how many requests per second you will have after you reduced the interval from 3 to 0, taking into account that the number of clients is increasing with 10% per month etc etc.

The main idea is that you should do some performance testing for some API and save the scripts in order to see if your future modification are slowing down the system too much. Without having this it is quite hard to guess if it ok or not to change configuration parameters.

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You might want to try out long-polling. For our Weblogic servers, we don't get any problems unless we let the poll request go to 5 minutes, so we keep it to 4, then give it a 1 second rest before starting again. We have a couple of hundred total users, with 60-70 on it hard core all day. The thing to keep in mind is that you're basically turning intermittent user requests into what amounts to almost always connected telnet sessions. Depending on the browser your users are using it can implications from that as well, but overall we've been very pleased.