Node takes very long time to response to the JSON request

I've implemented the chat application using node.js. The program open the connection with the client and it'll response the new message when the EventEmitter emit "recv" event.

The problem is it takes very long time to response to other request when the server hold about 3 or 4 more streams. The chrome developer tool show the status of the request as pending. it took more than 5-30 second to reach the server(localhost). I use console.log to log when the new request is received by the node.js

I have no idea why there's a long pause. Is there any limit on chrome browser, no开发者_运维技巧de.js or any other stuffs i should know? Does the node delay when it hold too many request at the same time and how should i measure this value? Thank you

Chrome supports six simultaneous connections per domain, so if those are already in use, it will have to wait for one to close. If you want to know what's going on, use a packet capture program to check the actual network traffic.

Browsers are limited to certain number of parallel connections which applies to the same browser context - for example when you have opened let's say more than 6 tabs, then the connections will be queued and you will see them pending.

You can avoid this limitation, for example, by using unique poll subdomain for each client connection. This is how facebook workaround this limitation, however problem is with Firefox, where this workaround doesn't work and your connections will be queued when they reach the limit even when you use unique subdomains.

Other solution might be to use HTML5 local storage where you can take advantage of StorageEvent which propagate changes also to other tabs within the same browser. This is how StackOverflow chat is done. Advantage of this approach is that you need only one polling connection with the server, but disadvantage is lack of HTML5 local storage support in older browsers or different implementation in FF version < 4.