Add emerge --jobs-merge-wait-threshold option

lib/_emerge/Scheduler.py

@@ -229,6 +229,7 @@ def __init__(
         if max_jobs is None:
             max_jobs = 1
         self._set_max_jobs(max_jobs)
+        self._jobs_merge_wait_threshold = myopts.get("--jobs-merge-wait-threshold")
         self._running_root = trees[trees._running_eroot]["root_config"]
         self.edebug = 0
         if settings.get("PORTAGE_DEBUG", "") == "1":
@@ -1792,6 +1793,18 @@ def _is_work_scheduled(self):
     def _running_job_count(self):
         return self._jobs
 
+    def _can_add_job(self):
+        if not super()._can_add_job():
+            return False
+
+        if (
+            self._jobs_merge_wait_threshold is not None
+            and len(self._merge_wait_queue) >= self._jobs_merge_wait_threshold
+        ):
+            return False
+
+        return True
+
     def _schedule_tasks(self):
         while True:
             state_change = 0

lib/_emerge/main.py

@@ -1,4 +1,4 @@
-# Copyright 1999-2023 Gentoo Authors
+# Copyright 1999-2024 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
 import argparse
@@ -165,6 +165,7 @@ def __contains__(self, s):
         "--getbinpkgonly": y_or_n,
         "--ignore-world": y_or_n,
         "--jobs": valid_integers,
+        "--jobs-merge-wait-threshold": valid_integers,
         "--keep-going": y_or_n,
         "--load-average": valid_floats,
         "--onlydeps-with-ideps": y_or_n,
@@ -523,6 +524,10 @@ def parse_opts(tmpcmdline, silent=False):
             "help": "Specifies the number of packages to build " + "simultaneously.",
             "action": "store",
         },
+        "--jobs-merge-wait-threshold": {
+            "help": "Specifies the maximum number of queued merges that can exist when starting a new job.",
+            "action": "store",
+        },
         "--keep-going": {
             "help": "continue as much as possible after an error",
             "choices": true_y_or_n,
@@ -1033,6 +1038,24 @@ def parse_opts(tmpcmdline, silent=False):
 
         myoptions.jobs = jobs
 
+    if myoptions.jobs_merge_wait_threshold == "True":
+        myoptions.jobs_merge_wait_threshold = None
+
+    if myoptions.jobs_merge_wait_threshold:
+        try:
+            jobs_merge_wait_threshold = int(myoptions.jobs_merge_wait_threshold)
+        except ValueError:
+            jobs_merge_wait_threshold = 0
+
+        if jobs_merge_wait_threshold <= 0:
+            jobs_merge_wait_threshold = None
+            if not silent:
+                parser.error(
+                    f"Invalid --jobs-merge-wait-threshold: '{myoptions.jobs_merge_wait_threshold}'\n"
+                )
+
+        myoptions.jobs_merge_wait_threshold = jobs_merge_wait_threshold
+
     if myoptions.load_average == "True":
         myoptions.load_average = None
 

man/emerge.1

@@ -1,4 +1,4 @@
-.TH "EMERGE" "1" "May 2024" "Portage @VERSION@" "Portage"
+.TH "EMERGE" "1" "Jun 2024" "Portage @VERSION@" "Portage"
 .SH "NAME"
 emerge \- Command\-line interface to the Portage system
 .SH "SYNOPSIS"
@@ -693,6 +693,11 @@ Note that interactive packages currently force a setting
 of \fI\-\-jobs=1\fR. This issue can be temporarily avoided
 by specifying \fI\-\-accept\-properties=\-interactive\fR.
 .TP
+.BR \-\-jobs\-merge\-wait\-threshold[=COUNT]
+Specifies the maximum number of queued merges that can exist when
+starting a new job. With no argument, removes a previous merge wait
+threshold.
+.TP
 .BR "\-\-keep\-going [ y | n ]"
 Continue as much as possible after an error. When an error occurs,
 dependencies are recalculated for remaining packages and any with