Exception when running the garbage collection during new identity
During New Identity
we run some fancy code to make sure we are really have a clean state after closing and reopening the browser:
// Run garbage collection and cycle collection after window is gone.
// This ensures that blob URIs are forgotten.
window.addEventListener("unload", function (event) {
torbutton_log(3, "Initiating New Identity GC pass");
// Clear out potential pending sInterSliceGCTimer:
m_tb_domWindowUtils.runNextCollectorTimer();
// Clear out potential pending sICCTimer:
m_tb_domWindowUtils.runNextCollectorTimer();
// Schedule a garbage collection in 4000-1000ms...
m_tb_domWindowUtils.garbageCollect();
// To ensure the GC runs immediately instead of 4-10s from now, we need
// to poke it at least 11 times.
// We need 5 pokes for GC, 1 poke for the interSliceGC, and 5 pokes for CC.
// See nsJSContext::RunNextCollectorTimer() in
// https://mxr.mozilla.org/mozilla-central/source/dom/base/nsJSEnvironment.cpp#1970.
// XXX: We might want to make our own method for immediate full GC...
for (let poke = 0; poke < 11; poke++) {
m_tb_domWindowUtils.runNextCollectorTimer();
}
// And now, since the GC probably actually ran *after* the CC last time,
// run the whole thing again.
m_tb_domWindowUtils.garbageCollect();
for (let poke = 0; poke < 11; poke++) {
m_tb_domWindowUtils.runNextCollectorTimer();
}
That leads to an exception in chrome://extensions/content/ext-tabs-base.js
in some cases at
get frameLoader() {
return this.browser.frameLoader;
as it is not guaranteed that browser
is still a thing during that operation. An example where this occurs is
- On
about:page
open the link to our newsletter in a new tab - Open the browser console
- Hit
New Identity
This got reported on our blog https://blog.torproject.org/comment/279507#comment-279507 ff.