From 1835ca1918a4408e4ea1ba778919cea2c9a3b53e Mon Sep 17 00:00:00 2001
From: epriestley <git@epriestley.com>
Date: Mon, 9 May 2022 10:04:09 -0700
Subject: [PATCH] Remove the "25% of active pool" growth rate throttle from
 Drydock

Summary:
Ref T13677. Drydock has a hard-coded and fairly arbitrary limit which prevents a resource pool from growing more than 25% at once.

This is vaguely reasonable for resources which allocate quickly, but suffocating for slower resources. It's also wholly arbitrary, and the "one per lease" limit introduced in D21807 should do a better job of covering the same ground while generally being more reasonable, expected, and predictable.

Test Plan: Ran Drydock allocations without the throttle, saw faster pool growth.

Subscribers: yelirekim, PHID-OPKG-gm6ozazyms6q6i22gyam

Maniphest Tasks: T13677

Differential Revision: https://secure.phabricator.com/D21808
---
 .../DrydockBlueprintImplementation.php        | 46 +++++--------------
 1 file changed, 11 insertions(+), 35 deletions(-)

diff --git a/src/applications/drydock/blueprint/DrydockBlueprintImplementation.php b/src/applications/drydock/blueprint/DrydockBlueprintImplementation.php
index c5e9f811b5..27ba6e623f 100644
--- a/src/applications/drydock/blueprint/DrydockBlueprintImplementation.php
+++ b/src/applications/drydock/blueprint/DrydockBlueprintImplementation.php
@@ -506,28 +506,21 @@ abstract class DrydockBlueprintImplementation extends Phobject {
   protected function shouldLimitAllocatingPoolSize(
     DrydockBlueprint $blueprint) {
 
-    // TODO: If this mechanism sticks around, these values should be
-    // configurable by the blueprint implementation.
-
     // Limit on total number of active resources.
     $total_limit = $this->getConcurrentResourceLimit($blueprint);
-
-    // Always allow at least this many allocations to be in flight at once.
-    $min_allowed = 1;
-
-    // Allow this fraction of allocating resources as a fraction of active
-    // resources.
-    $growth_factor = 0.25;
+    if ($total_limit === null) {
+      return false;
+    }
 
     $resource = new DrydockResource();
-    $conn_r = $resource->establishConnection('r');
+    $conn = $resource->establishConnection('r');
 
     $counts = queryfx_all(
-      $conn_r,
-      'SELECT status, COUNT(*) N FROM %T
+      $conn,
+      'SELECT status, COUNT(*) N FROM %R
         WHERE blueprintPHID = %s AND status != %s
         GROUP BY status',
-      $resource->getTableName(),
+      $resource,
       $blueprint->getPHID(),
       DrydockResourceStatus::STATUS_DESTROYED);
     $counts = ipull($counts, 'N', 'status');
@@ -539,29 +532,12 @@ abstract class DrydockBlueprintImplementation extends Phobject {
 
     // If we're at the limit on total active resources, limit additional
     // allocations.
-    if ($total_limit !== null) {
-      $n_total = ($n_alloc + $n_active + $n_broken + $n_released);
-      if ($n_total >= $total_limit) {
-        return true;
-      }
+    $n_total = ($n_alloc + $n_active + $n_broken + $n_released);
+    if ($n_total >= $total_limit) {
+      return true;
     }
 
-    // If the number of in-flight allocations is fewer than the minimum number
-    // of allowed allocations, don't impose a limit.
-    if ($n_alloc < $min_allowed) {
-      return false;
-    }
-
-    $allowed_alloc = (int)ceil($n_active * $growth_factor);
-
-    // If the number of in-flight allocation is fewer than the number of
-    // allowed allocations according to the pool growth factor, don't impose
-    // a limit.
-    if ($n_alloc < $allowed_alloc) {
-      return false;
-    }
-
-    return true;
+    return false;
   }
 
 }