[tbb-bugs] #20890 [Applications/Tor Browser]: Could not connect to Tor control port

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#20890: Could not connect to Tor control port
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 Reporter:  torrc591                  |          Owner:  brade
     Type:  defect                    |         Status:  assigned
 Priority:  Very High                 |      Milestone:
Component:  Applications/Tor Browser  |        Version:
 Severity:  Critical                  |     Resolution:
 Keywords:                            |  Actual Points:
Parent ID:                            |         Points:
 Reviewer:                            |        Sponsor:
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Changes (by GreenReaper):

 * owner:  tbb-team => brade
 * status:  needs_information => assigned


Comment:

 The issue in my case is intermittent and subsequent launches may or may
 succeed. More often than not, they do not. Attached are logs from both
 cases.

 When it fails, it does so on the third attempt to AUTHENTICATE (the first
 one seem to be refused quickly, while the second times out; the question
 is if that repeats):
 `TorLauncher NOTE: failed to open authenticated connection: [Exception...
 "Component returned failure code: 0x804b000e (NS_ERROR_NET_TIMEOUT)
 [nsIBinaryInputStream.readBytes]"  nsresult: "0x804b000e
 (NS_ERROR_NET_TIMEOUT)"`

 I suspect seeds of this issue were introduced early on when a 15-second
 timeout was added:
 https://gitweb.torproject.org/tor-launcher.git/commit/src/components/tl-
 protocol.js?id=bded277453e87892eca5a2834ecce079accf88a9

 TorSendCommand tries a few times according to the code, but eventually
 it's game over. This is an issue for slow devices in general, but attempts
 to increase Tor security may also have increased its startup time.

 My device is a Lenovo x120e with a 2011 dual-core mobile AMD Fusion CPU
 (E-350). It is entirely possible that insufficient time is being given for
 the launch, especially if other tasks are running in the background. A
 "good" launch is 30 seconds, and Tor.exe takes up the entirety of one core
 for at least 20 of those.

 As for why it tends to work for the first launch, perhaps this is because
 according to
 https://gitweb.torproject.org/tor-launcher.git/tree/src/components/tl-
 process.js
 `// Start tor with networking disabled if first run`

 Alternatively, maybe addons are installed or updated, or the necessary
 files are already in memory/cache, and not fragmented; or Tor has less
 state cached and so less to look up. I think you need to try running it in
 combination with other high-CPU tasks on a limited number of slow cores
 and see how it falls over.

 I suspect #24776 is the same issue; Windows 7 Starter Edition is
 restricted to low-class devices.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/20890#comment:6>
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