backend: provide per-arch & per-owner worker limit

The default "max_workers" limit might be too large (e.g. in Fedora Copr
it is 45) compared to the number of available workers of some
architecture type (e.g. for s390x there's now max 18 workers, and
ppc64le is often limited too due to #2869).  This patch then brings
another FUP mitigation.

backend/conf/copr-be.conf.example

@@ -42,6 +42,10 @@ sleeptime=30
 # Maximum number of concurrently running tasks per architecture.
 #builds_max_workers_arch=x86_64=10,ppc64le=12
 
+# Maximum number of concurrent build workers per architecture and owner.  For
+# example, give at most 15 ppc64le and 10 s390x machines to one copr owner:
+#build_max_workers_arch_per_owner=ppc64le=15,s390x=10
+
 # Maximum number of concurrently running tasks per project owner.
 #builds_max_workers_owner=20
 

backend/copr_backend/daemons/build_dispatcher.py

@@ -6,6 +6,7 @@
 from copr_backend.dispatcher import BackendDispatcher
 from copr_backend.rpm_builds import (
     ArchitectureWorkerLimit,
+    ArchitectureUserWorkerLimit,
     BuildTagLimit,
     RPMBuildWorkerManager,
     BuildQueueTask,
@@ -83,9 +84,14 @@ def __init__(self, backend_opts):
         super().__init__(backend_opts)
         self.max_workers = backend_opts.builds_max_workers
 
-        for tag_type in ["arch", "tag"]:
-            lclass = ArchitectureWorkerLimit if tag_type == "arch" else \
-                     BuildTagLimit
+        for tag_type in ["arch", "tag", "arch_per_owner"]:
+            match tag_type:
+                case "arch":
+                    lclass = ArchitectureWorkerLimit
+                case "tag":
+                    lclass = BuildTagLimit
+                case "arch_per_owner":
+                    lclass = ArchitectureUserWorkerLimit
             for tag, limit in backend_opts.builds_limits[tag_type].items():
                 self.log.info("setting %s(%s) limit to %s", tag_type, tag, limit)
                 self.limits.append(lclass(tag, limit))

backend/copr_backend/helpers.py

@@ -215,9 +215,9 @@ def _get_limits_conf(parser):
             "option.  Please use format: "
             "builds_max_workers_{0} = {1}1=COUNT,{1}2=COUNT")
     err2 = ("Duplicate left value '{}' in 'builds_max_workers_{}' configuration")
-    limits = {"arch": {}, "tag": {}}
+    limits = {"arch": {}, "tag": {}, "arch_per_owner": {}}
 
-    for config_type in ["arch", "tag"]:
+    for config_type in ["arch", "tag", "arch_per_owner"]:
         option = "builds_max_workers_{}".format(config_type)
         raw = _get_conf(parser, "backend", option, None)
         if raw:

backend/copr_backend/rpm_builds.py

@@ -2,7 +2,11 @@
 Abstraction for RPM and SRPM builds on backend.
 """
 
-from copr_common.worker_manager import WorkerManager, PredicateWorkerLimit
+from copr_common.worker_manager import (
+    GroupWorkerLimit,
+    WorkerManager,
+    PredicateWorkerLimit,
+)
 from copr_backend.worker_manager import BackendQueueTask
 from copr_backend.helpers import get_chroot_arch
 
@@ -133,6 +137,19 @@ def predicate(x):
         super().__init__(predicate, limit, name="arch_{}".format(architecture))
 
 
+class ArchitectureUserWorkerLimit(GroupWorkerLimit):
+    """
+    Limit number of machines of specific architecture we give to a single
+    Copr owner (user or group).
+    """
+    def __init__(self, architecture, limit):
+        super().__init__(
+            lambda x: f"{x.requested_arch}_{x.owner}",
+            limit,
+            name=f"arch_{architecture}_owner",
+        )
+
+
 class BuildTagLimit(PredicateWorkerLimit):
     """
     Limit the amount of concurrently running builds per given build tag.

backend/tests/test_config_reader.py

@@ -37,7 +37,8 @@ def get_minimal_config_file(self):
     def test_minimal_file_and_defaults(self):
         opts = BackendConfigReader(self.get_minimal_config_file()).read()
         assert opts.destdir == "/tmp"
-        assert opts.builds_limits == {'arch': {}, 'tag': {}, 'owner': 20, 'sandbox': 10}
+        assert opts.builds_limits == {'arch': {}, 'tag': {}, 'owner': 20,
+                                      'sandbox': 10, 'arch_per_owner': {}}
 
     def test_correct_build_limits(self):
         opts = BackendConfigReader(
@@ -48,6 +49,7 @@ def test_correct_build_limits(self):
                     "builds_max_workers_tag = Power9=9\n"
                     "builds_max_workers_owner = 5\n"
                     "builds_max_workers_sandbox = 3\n"
+                    "builds_max_workers_arch_per_owner = ppc64le=11, s390x=5\n"
                 ))).read()
         assert opts.builds_limits == {
             'arch': {
@@ -58,7 +60,11 @@ def test_correct_build_limits(self):
                 'Power9': 9,
             },
             'owner': 5,
-            'sandbox': 3
+            'sandbox': 3,
+            'arch_per_owner': {
+                'ppc64le': 11,
+                's390x': 5,
+            },
         }
 
     @pytest.mark.parametrize("broken_config", [

backend/tests/test_worker_limits.py

@@ -12,6 +12,7 @@
 from copr_backend.worker_manager import BackendQueueTask
 from copr_backend.rpm_builds import (
     ArchitectureWorkerLimit,
+    ArchitectureUserWorkerLimit,
     BuildTagLimit,
     BuildQueueTask,
 )
@@ -23,16 +24,19 @@
 }, {
     "build_id": 7,
     "task_id": "7-fedora-rawhide-x86_64",
+    "chroot": "fedora-rawhide-x86_64",
     "project_owner": "cecil",
     "sandbox": "sb1",
 }, {
     "build_id": 4,
     "task_id": "7-fedora-32-x86_64",
+    "chroot": "fedora-32-x86_64",
     "project_owner": "bedrich",
     "sandbox": "sb2",
 }, {
     "build_id": 4,
     "task_id": "7-fedora-31-x86_64",
+    "chroot": "fedora-31-x86_64",
     "project_owner": "bedrich",
     "sandbox": "sb2",
     "tags": ["special_requirement"],
@@ -115,6 +119,7 @@ def test_worker_limit_info():
         GroupWorkerLimit(lambda x: x.sandbox, 2, name='sandbox'),
         ArchitectureWorkerLimit("x86_64", 3),
         ArchitectureWorkerLimit("aarch64", 2),
+        ArchitectureUserWorkerLimit("aarch64", 2),
         BuildTagLimit("special_requirement", 1),
     ]
     tasks = [BuildQueueTask(t) for t in TASKS]
@@ -128,8 +133,9 @@ def test_worker_limit_info():
         'w:7-fedora-32-x86_64, w:7-fedora-31-x86_64',
         "limit info: Unnamed 'GroupWorkerLimit' limit, counter: cecil=2, bedrich=2",
         "limit info: 'sandbox', counter: sb1=1, sb2=2",
-        "limit info: 'arch_x86_64'",
+        "limit info: 'arch_x86_64', matching: w:7-fedora-rawhide-x86_64, w:7-fedora-32-x86_64, w:7-fedora-31-x86_64",
         "limit info: 'arch_aarch64'",
+        "limit info: 'arch_aarch64_owner', counter: None_cecil=1, x86_64_cecil=1, x86_64_bedrich=2",
         "limit info: 'tag_special_requirement', matching: w:7-fedora-31-x86_64",
     ]