bug#61350: Eglot over Tramp freezes with large project

["João Távora" <joaotavora@gmail.com>]

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João Távora <joaotavora@gmail.com> writes:

> Stefan Monnier <monnier@iro.umontreal.ca> writes:

> Does that "some" include _this_ problem?  Let's take this one for
> example.
>
>    make -C test filenotify-tests
>    SELECTOR=file-notify-test04-autorevert

Sorry, here I meant to type 'file-notify-test04-autorevert-remote'

> We know this was introduced by the recent changes
> 54ef338ba3670415cf47fabc33a92d4904707c7e.

FWIW, I've run the following experiment:

1. Reverted 54ef338ba3670415cf47fabc33a92d4904707c7e

2. Applied a simpler, more conservative, patch, discussed with Michael
   before.  The patch keeps the protocol for tramp-a-p-o untouched.  It
   simply adds a "while" to the 'a-p-o' call issued for "related"
   processes.

3. Ran the filenotify test suite.  All but one tests pass.
   'file-notify-test04-autorevert-remote' now passes.  The failure I
   get, 'file-notify-test06-dir-validity-remote', is _also_ in Emacs 29

4. Removed the Tramp-specific Eglot workaround in
   lisp/progmodes/eglot.el which disabled Controlmaster.

5. Ran the Eglot-over-Tramp experiment with the JDTLS LSP server
   multiple times with 0% failures.

6. The two Tramp-related failures in the eglot-tests.el test suite are
   _also_ fixed.  Ran this multiple times, 0% failures.

It seems evident that my simpler patch puts us in a much better place
than we are now, so I propose we push them.  Patches are attached.

Of course, we can continue to explore other more elegant solutions.

João


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From f8ea932928fe37573d28c197c1c9d2da9a08089d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20T=C3=A1vora?= <joaotavora@gmail.com>
Date: Wed, 15 Mar 2023 19:18:00 +0000
Subject: [PATCH 1/3] Revert "Improve Tramp processes to accept output over the
 same socket"

This reverts commit 54ef338ba3670415cf47fabc33a92d4904707c7e.
---
 lisp/net/tramp-adb.el      |  2 +-
 lisp/net/tramp-gvfs.el     |  2 +-
 lisp/net/tramp-sh.el       | 14 +-------------
 lisp/net/tramp-smb.el      |  6 +++---
 lisp/net/tramp-sudoedit.el |  2 +-
 lisp/net/tramp.el          | 33 +++++++++------------------------
 6 files changed, 16 insertions(+), 43 deletions(-)

diff --git a/lisp/net/tramp-adb.el b/lisp/net/tramp-adb.el
index d338201ab72..64f45e7958d 100644
--- a/lisp/net/tramp-adb.el
+++ b/lisp/net/tramp-adb.el
@@ -990,7 +990,7 @@ tramp-adb-handle-make-process
 				  (progn
 				    (goto-char (point-min))
 				    (not (search-forward "\n" nil t)))
-			        (tramp-accept-process-output p))
+			        (tramp-accept-process-output p 0))
 			      (delete-region (point-min) (point)))
 			    ;; Provide error buffer.  This shows only
 			    ;; initial error messages; messages
diff --git a/lisp/net/tramp-gvfs.el b/lisp/net/tramp-gvfs.el
index c1ad37de1d2..266724c587f 100644
--- a/lisp/net/tramp-gvfs.el
+++ b/lisp/net/tramp-gvfs.el
@@ -1469,7 +1469,7 @@ tramp-gvfs-handle-file-notify-add-watch
 	(set-process-sentinel p #'tramp-file-notify-process-sentinel)
 	;; There might be an error if the monitor is not supported.
 	;; Give the filter a chance to read the output.
-	(while (tramp-accept-process-output p))
+	(while (tramp-accept-process-output p 0))
 	(unless (process-live-p p)
 	  (tramp-error
 	   p 'file-notify-error "Monitoring not supported for `%s'" file-name))
diff --git a/lisp/net/tramp-sh.el b/lisp/net/tramp-sh.el
index 882b79b3ee7..48ebfff6cfe 100644
--- a/lisp/net/tramp-sh.el
+++ b/lisp/net/tramp-sh.el
@@ -2424,10 +2424,6 @@ tramp-do-copy-or-rename-file-out-of-band
 		      copy-program copy-args)))
 		(tramp-message v 6 "%s" (string-join (process-command p) " "))
 		(process-put p 'vector v)
-		;; This is neded for ssh or PuTTY based processes, and
-		;; only if the respective options are set.  Perhaps,
-		;; the setting could be more fine-grained.
-		(process-put p 'shared-socket t)
 		(process-put p 'adjust-window-size-function #'ignore)
 		(set-process-query-on-exit-flag p nil)
 
@@ -3757,10 +3753,6 @@ tramp-sh-handle-file-notify-add-watch
 	   (string-join sequence " "))
 	(tramp-message v 6 "Run `%s', %S" (string-join sequence " ") p)
 	(process-put p 'vector v)
-	;; This is neded for ssh or PuTTY based processes, and only if
-	;; the respective options are set.  Perhaps, the setting could
-	;; be more fine-grained.
-	(process-put p 'shared-socket t)
 	;; Needed for process filter.
 	(process-put p 'events events)
 	(process-put p 'watch-name localname)
@@ -3769,7 +3761,7 @@ tramp-sh-handle-file-notify-add-watch
 	(set-process-sentinel p #'tramp-file-notify-process-sentinel)
 	;; There might be an error if the monitor is not supported.
 	;; Give the filter a chance to read the output.
-	(while (tramp-accept-process-output p))
+	(while (tramp-accept-process-output p 0))
 	(unless (process-live-p p)
 	  (tramp-error
 	   p 'file-notify-error "Monitoring not supported for `%s'" file-name))
@@ -5121,10 +5113,6 @@ tramp-maybe-open-connection
 		;; Set sentinel and query flag.  Initialize variables.
 		(set-process-sentinel p #'tramp-process-sentinel)
 		(process-put p 'vector vec)
-		;; This is neded for ssh or PuTTY based processes, and
-		;; only if the respective options are set.  Perhaps,
-		;; the setting could be more fine-grained.
-		(process-put p 'shared-socket t)
 		(process-put p 'adjust-window-size-function #'ignore)
 		(set-process-query-on-exit-flag p nil)
 		(setq tramp-current-connection (cons vec (current-time)))
diff --git a/lisp/net/tramp-smb.el b/lisp/net/tramp-smb.el
index bb4ab9e3057..1aa4520eeb6 100644
--- a/lisp/net/tramp-smb.el
+++ b/lisp/net/tramp-smb.el
@@ -757,7 +757,7 @@ tramp-smb-action-get-acl
   "Read ACL data from connection buffer."
   (unless (process-live-p proc)
     ;; Accept pending output.
-    (while (tramp-accept-process-output proc))
+    (while (tramp-accept-process-output proc 0))
     (with-current-buffer (tramp-get-connection-buffer vec)
       ;; There might be a hidden password prompt.
       (widen)
@@ -1363,7 +1363,7 @@ tramp-smb-action-set-acl
   "Set ACL data."
   (unless (process-live-p proc)
     ;; Accept pending output.
-    (while (tramp-accept-process-output proc))
+    (while (tramp-accept-process-output proc 0))
     (tramp-message
      vec 10 "\n%s" (tramp-get-buffer-string (tramp-get-connection-buffer vec)))
     (throw 'tramp-action 'ok)))
@@ -2023,7 +2023,7 @@ tramp-smb-wait-for-output
 
       ;; Read pending output.
       (while (not (re-search-forward tramp-smb-prompt nil t))
-	(while (tramp-accept-process-output p))
+	(while (tramp-accept-process-output p 0))
 	(goto-char (point-min)))
       (tramp-message vec 6 "\n%s" (buffer-string))
 
diff --git a/lisp/net/tramp-sudoedit.el b/lisp/net/tramp-sudoedit.el
index 3cacde2468c..abb9afc570b 100644
--- a/lisp/net/tramp-sudoedit.el
+++ b/lisp/net/tramp-sudoedit.el
@@ -692,7 +692,7 @@ tramp-sudoedit-action-sudo
   "Check, whether a sudo process has finished.  Remove unneeded output."
   ;; There might be pending output for the exit status.
   (unless (process-live-p proc)
-    (while (tramp-accept-process-output proc))
+    (while (tramp-accept-process-output proc 0))
     ;; Delete narrowed region, it would be in the way reading a Lisp form.
     (goto-char (point-min))
     (widen)
diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index b6e985db6b1..47173b95bea 100644
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -5087,11 +5087,6 @@ tramp-handle-make-process
 	    ;; t.  See Bug#51177.
 	    (when filter
 	      (set-process-filter p filter))
-	    (process-put p 'vector v)
-	    ;; This is neded for ssh or PuTTY based processes, and
-	    ;; only if the respective options are set.  Perhaps, the
-	    ;; setting could be more fine-grained.
-	    (process-put p 'shared-socket t)
 	    (process-put p 'remote-command orig-command)
 	    (tramp-set-connection-property p "remote-command" orig-command)
 
@@ -5494,7 +5489,7 @@ tramp-handle-file-notify-rm-watch
   ;; There might be pending output.  Avoid problems with reentrant
   ;; call of Tramp.
   (ignore-errors
-    (while (tramp-accept-process-output proc)))
+    (while (tramp-accept-process-output proc 0)))
   (tramp-message proc 6 "Kill %S" proc)
   (delete-process proc))
 
@@ -5646,13 +5641,13 @@ tramp-action-process-alive
   "Check, whether a process has finished."
   (unless (process-live-p proc)
     ;; There might be pending output.
-    (while (tramp-accept-process-output proc))
+    (while (tramp-accept-process-output proc 0))
     (throw 'tramp-action 'process-died)))
 
 (defun tramp-action-out-of-band (proc vec)
   "Check, whether an out-of-band copy has finished."
   ;; There might be pending output for the exit status.
-  (while (tramp-accept-process-output proc))
+  (while (tramp-accept-process-output proc 0))
   (cond ((and (not (process-live-p proc))
 	      (zerop (process-exit-status proc)))
 	 (tramp-message	vec 3 "Process has finished.")
@@ -5683,7 +5678,7 @@ tramp-process-one-action
     (while (not found)
       ;; Reread output once all actions have been performed.
       ;; Obviously, the output was not complete.
-      (while (tramp-accept-process-output proc))
+      (while (tramp-accept-process-output proc 0))
       (setq todo actions)
       (while todo
 	(setq item (pop todo)
@@ -5800,21 +5795,11 @@ with-tramp-locked-connection
 	   ,@body)
        (tramp-flush-connection-property ,proc "locked"))))
 
-(defun tramp-accept-process-output (proc &optional _timeout)
+(defun tramp-accept-process-output (proc &optional timeout)
   "Like `accept-process-output' for Tramp processes.
 This is needed in order to hide `last-coding-system-used', which is set
 for process communication also.
 If the user quits via `C-g', it is propagated up to `tramp-file-name-handler'."
-  (declare (advertised-calling-convention (proc) "29.2"))
-  ;; There could be other processes which use the same socket for
-  ;; communication.  This could block the output for the current
-  ;; process.  Read such output first.  (Bug#61350)
-  (when-let (((process-get proc 'shared-socket))
-	     (v (process-get proc 'vector)))
-    (dolist (p (delq proc (process-list)))
-      (when (tramp-file-name-equal-p v (process-get p 'vector))
-	(accept-process-output p 0 nil t))))
-
   (with-current-buffer (process-buffer proc)
     (let ((inhibit-read-only t)
 	  last-coding-system-used
@@ -5824,10 +5809,10 @@ tramp-accept-process-output
 	;; JUST-THIS-ONE is set due to Bug#12145.  `with-local-quit'
 	;; returns t in order to report success.
 	(if (with-local-quit
-	      (setq result (accept-process-output proc 0 nil t)) t)
+	      (setq result (accept-process-output proc timeout nil t)) t)
 	    (tramp-message
-	     proc 10 "%s %s %s\n%s"
-	     proc (process-status proc) result (buffer-string))
+	     proc 10 "%s %s %s %s\n%s"
+	     proc timeout (process-status proc) result (buffer-string))
 	  ;; Propagate quit.
 	  (keyboard-quit)))
       result)))
@@ -6840,7 +6825,7 @@ tramp-interrupt-process
                  (tramp-get-remote-null-device (process-get proc 'vector))))
 	;; Wait, until the process has disappeared.  If it doesn't,
 	;; fall back to the default implementation.
-        (while (tramp-accept-process-output proc))
+        (while (tramp-accept-process-output proc 0))
 	(not (process-live-p proc))))))
 
 (add-hook 'interrupt-process-functions #'tramp-interrupt-process)
-- 
2.39.2


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From 16e93416780e416d27ed514e3d8a876405a4f4bc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20T=C3=A1vora?= <joaotavora@gmail.com>
Date: Wed, 15 Mar 2023 20:02:43 +0000
Subject: [PATCH 3/3] Simpler fix for bug#61350

* lisp/net/tramp.el (tramp-accept-process-output): Accept process
from related processes.
---
 lisp/net/tramp.el | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index 47173b95bea..885b29f9471 100644
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -5800,6 +5800,11 @@ tramp-accept-process-output
 This is needed in order to hide `last-coding-system-used', which is set
 for process communication also.
 If the user quits via `C-g', it is propagated up to `tramp-file-name-handler'."
+  (when-let (((process-get proc 'shared-socket))
+	     (v (process-get proc 'vector)))
+    (dolist (p (delq proc (process-list)))
+      (when (tramp-file-name-equal-p v (process-get p 'vector))
+	(while (accept-process-output p 0 nil t)))))
   (with-current-buffer (process-buffer proc)
     (let ((inhibit-read-only t)
 	  last-coding-system-used
-- 
2.39.2