Chrome hangs after certain amount of data transfered - waiting for available socket

Explanation:

This problem occurs because Chrome allows up to 6 open connections by default. So if you're streaming multiple media files simultaneously from 6 <video> or <audio> tags, the 7th connection (for example, an image) will just hang, until one of the sockets opens up. Usually, an open connection will close after 5 minutes of inactivity, and that's why you're seeing your .pngs finally loading at that point.

Solution 1:

You can avoid this by minimizing the number of media tags that keep an open connection. And if you need to have more than 6, make sure that you load them last, or that they don't have attributes like preload="auto".

Solution 2:

If you're trying to use multiple sound effects for a web game, you could use the Web Audio API. Or to simplify things, just use a library like SoundJS, which is a great tool for playing a large amount of sound effects / music tracks simultaneously.

Solution 3: Force-open Sockets (Not recommended)

If you must, you can force-open the sockets in your browser (In Chrome only):

1. Go to the address bar and type chrome://net-internals.
2. Select Sockets from the menu.
3. Click on the Flush socket pools button.

This solution is not recommended because you shouldn't expect your visitors to follow these instructions to be able to view your site.

Looks like you are hitting the limit on connections per server. I see you are loading a lot of static files and my advice is to separate them on subdomains and serve them directly with Nginx for example.

• Create a subdomain called img.yoursite.com and load all your imagesfrom there.

• Create a subdomain called scripts.yourdomain.com and load all your JS and CSS files from there.

• Create a subdomain called sounds.yoursite.com and load all your MP3s from there... etc..

Nginx has great options for directly serving static files and managing the static files caching.

The message:

Waiting for available socket...

is shown, because you've reached a limit on the ssl_socket_pool either per Host, Proxy or Group.

Here are the maximum number of HTTP connections which you can make with a Chrome browser:

• The maximum number of connections per proxy is 32 connections. This can be changed in Policy List.

• Maximum per Host: 6 connections.

  This is likely hardcoded in the source code of the web browser, so you can't change it.

• Total 256 HTTP connections pooled per browser.

^{Source: Enterprise networking for Chrome devices}

The above limits can be checked or flushed at chrome://net-internals/#sockets (or in real-time at chrome://net-internals/#events&q=type:SOCKET%20is:active).

Your issue with audio can be related to Chrome bug 162627 where HTML5 audio fails to load and it hits max simultaneous connections per server:proxy. This is still active issue at the time of writing (2016).

Much older issue related to HTML5 video request stay pending, then it's probably related to Issue #234779 which has been fixed 2014. And related to SPDY which can be found in Issue 324653: SPDY issue: waiting for available sockets, but this was already fixed in 2014, so probably it's not related.

Other related issue now marked as duplicate can be found in Issue 401845: Failure to preload audio metadata. Loaded only 6 of 10+ which was related to the problem with the media player code leaving a bunch of paused requests hanging around.

This also may be related to some Chrome adware or antivirus extensions using your sockets in the backgrounds (like Sophos or Kaspersky), so check for Network activity in DevTools.