Electrolysis/plugins

typical messaging deadlocks

case #1:

chrome -> sync ipc -> plugin -------+
                                    |
chrome <- sync sendmessage <--------+

case #2:

chrome -> sync sendmessage -> plugin -+
                                      |
chrome <- sync ipc <------------------+

case #3:

chrome -> sync ipc -> plugin -> plugin never responds back but keep pumping messages

non-e10s mitigation

case #1:

chrome -> sync ipc -> plugin ---------------------+
                                                  |
chrome | windowsmessageloop <- sync sendmessage <-+

case #2:

• various tricks

case #3:

• plugin hang dialog

e10s mitigation

chrome -> sync ipc | plugin

• never happens

chrome -> sync sendmessage -> plugin

• happens while chrome is dispatching messages, no sync/rpc calls on the stack?
• content could be in a sync call to either when this happens

chrome -> sync ipc -> content -> sync ipc -> plugin -> sync ipc | chrome

• never happens

chrome -> sync ipc -> content -> sync ipc -> plugin -> sync sendmessage -> chrome

• can happen?

content -> sync ipc -> plugin -> plugin never responds back but keep pumping messages

• content hang?

plugin deadlock

since the plugin's main thread is bound to chrome's main thread, if either slows down, or hangs, they both slow down or hang.

non-e10s mitigation

none

e10s mitigation

none

e10s notes:

• the content process runs freely initially when chrome or plugin hang, until it sends a sync message to either.
• content's main thread isn't caught up in the attached message queues problem afaict.
  • media related code migth break this if there's native ui and chrome parenting going on.