title: Is there a size limit for HTTP response headers on Google App Engine?
body: <p>I was trying to run a profiler on some handler code up on appspot and was looking for a way to show the pstats output without writing directly to the response body (which is problematic for handlers responding with structured data such as JSON).</p>
  
  <p>I decided to try writing the output to the response header, and added some js to my html-rendering handlers that could parse the header and <code>console.log()</code> it (turned out to be pretty simple and convenient to work with). For the non-html rendering handlers, I was thinking I might try and build a chrome extension to do something similar, but of course, whenever I'm making an ajax call to such a handler, the calling page (with the js to parse the header) can step in and handle the display.</p>
  
  <p>All this looked good as I was testing on <code>dev_appserver</code>, but then I deployed to appspot and found that my custom header never showed up. I have similar pieces of code in this project that track the elapsed execution time of certain operations, and the custom headers I write that stuff to shows up fine.</p>
  
  <p>I'm assuming there's a limit in place on appspot python runtime process that omits the header if it's greater than a certain length, but I don't see the size published anywhere on the developer site.</p>
  
  <p>If there is in fact a limit, does anyone know what it is?</p>