More PR feedback

doc/fork_support.md

@@ -1,22 +1,24 @@
 # Background #
 
-In Python multithreading is ineffective at concurrency for CPU bound tasks
+In Python, multithreading is ineffective at concurrency for CPU bound tasks
-due to the GIL.
+due to the GIL (global interpreter lock).  Extension modules can release
-(global interpreter lock).  Users use multiprocessing, subprocess, 
+the GIL in CPU bound tasks, but that isn't an option in pure Python.
-and concurrent.futures.ProcessPoolExecutor, to work around the GIL.
+Users use libraries such as multiprocessing, subprocess, concurrent.futures.ProcessPoolExecutor,
-These modules call fork() underneath the hood. Various issues have
+etc, to work around the GIL. These modules call fork() underneath the hood. Various issues have
-been reported when using these modules with gRPC Python.
+been reported when using these modules with gRPC Python.  gRPC Python wraps
-Historically, we didn't support forking in gRPC, but some users seem
+gRPC core, which uses multithreading for performance, and hence doesn't support fork().
+Historically, we didn't support forking in gRPC, but some users seemed
 to be doing fine until their code started to break on version 1.6.  This was
 likely caused by the addition of background c-threads and a background
 Python thread.
 
 # Current Status #
-## 1.7 ##
+
-A pthread_atfork() handler was added in 1.7 to automatically shut down
+## 1.11 ##
-the background c-threads when fork was called.  This does not shut down the
+The background Python thread was removed entirely.  This allows forking
-background Python thread, so users could not have any open channels when
+after creating a channel.  However, the channel must not have issued any
-forking().
+RPCs prior to the fork.  Attempting to fork with an active channel that
+has been used can result in deadlocks/corrupted wire data.
 
 ## 1.9 ##
 A regression was noted in cases where users are doing fork/exec. This
@@ -28,22 +30,17 @@ off the handler using env flag ```GRPC_ENABLE_FORK_SUPPORT=False```.
 This should be set whenever a user expects to always call exec
 immediately following fork.  It will disable the fork handlers.
 
-## 1.11 ##
+## 1.7 ##
-The background Python thread was removed entirely.  This allows forking
+A pthread_atfork() handler was added in 1.7 to automatically shut down
-after creating a channel.  However, the channel cannot be used by both the
+the background c-threads when fork was called.  This does not shut down the
-parent and child process after the fork.  Additionaly, the process should
+background Python thread, so users could not have any open channels when
-not fork if there are any active RPCs on the channel.
+forking().
 
 # Future Work #
+
 ## 1.13 ##
 The workaround when using fork/exec by setting
-```GRPC_ENABLE_FORK_SUPPORT=False``` should no longer be needed.  Now the fork
+```GRPC_ENABLE_FORK_SUPPORT=False``` should no longer be needed.  Following
-handlers are automatically not run when multiple threads are calling
+[this PR](https://github.com/grpc/grpc/pull/14647), fork
+handlers will not automatically run when multiple threads are calling
 into gRPC.
-
-
-## 1.1x ##
-We would like to support forking and using the channel from both the parent
-and child process.  Additionally, we would like to support servers that
-use a prefork model, where the child processes accept the connections
-and handle requests.