Merge ~hloeung/content-cache-charm:cleanup into content-cache-charm:master

[Haw Loeung]

Assume 64-bit CPU, set max. threads and processes to 64

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[Paul Collins (pjdc)]

LGTM, observation inline.

review: Approve

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Change successfully merged at revision eb6c52390c6809405dabe14d3b435ec3fd293538

diff --git a/config.yaml b/config.yaml
index 7030778..03bf2eb 100644
--- a/config.yaml
+++ b/config.yaml
@@ -43,16 +43,16 @@ options:
     description: >
       Sets the number of HAProxy processes. If both processs and
       threads specified and using HAProxy 2.x and above, the number of
-      HAProxy threadsd will be configured using processes multiplied
-      by threads.
+      HAProxy threads will be configured using processes multiplied
+      by threads (max. 64).
   haproxy_threads:
     default: 0
     type: int
     description: >
       Sets the number of HAProxy threads. If both processs and
       threads specified and using HAProxy 2.x and above, the number of
-      HAProxy threadsd will be configured using processes multiplied
-      by threads.
+      HAProxy threads will be configured using processes multiplied
+      by threads (max. 64).
   log_retention:
     type: int
     default: 30
diff --git a/lib/haproxy.py b/lib/haproxy.py
index b21bcb4..02bec57 100644
--- a/lib/haproxy.py
+++ b/lib/haproxy.py
@@ -266,6 +266,10 @@ backend backend-{name}
             num_procs = 0
         if not num_threads:
             num_threads = 0
+        # Assume 64-bit CPU so limit processes and threads to 64.
+        # https://discourse.haproxy.org/t/architectural-limitation-for-nbproc/5270
+        num_procs = min(64, num_procs)
+        num_threads = min(64, num_threads)
         return (num_procs, num_threads)
 
     def render(self, config, num_procs=None, num_threads=None, monitoring_password=None, tls_cipher_suites=None):
diff --git a/tests/unit/test_haproxy.py b/tests/unit/test_haproxy.py
index e45d42b..cac29ca 100644
--- a/tests/unit/test_haproxy.py
+++ b/tests/unit/test_haproxy.py
@@ -219,6 +219,12 @@ class TestLibHAProxy(unittest.TestCase):
         self.assertEqual(haproxy._calculate_num_procs_threads(3, None), (3, 0))
         self.assertEqual(haproxy._calculate_num_procs_threads(None, None), (0, 4))
 
+        # Max. threads and procs ceiling 64
+        package_version.return_value = '2.0.13-2'
+        self.assertEqual(haproxy._calculate_num_procs_threads(2, 100), (0, 64))
+        self.assertEqual(haproxy._calculate_num_procs_threads(100, 0), (64, 0))
+        self.assertEqual(haproxy._calculate_num_procs_threads(100, 100), (0, 64))
+
     def test_get_parent_pid(self):
         haproxy = HAProxy.HAProxyConf(self.tmpdir)
         self.assertEqual(haproxy.get_parent_pid(pidfile='tests/unit/files/haproxy.pid'), 31337)