fix: changing max threads default

closes: #17483

Signed-off-by: Steve Hawkins <shawkins@redhat.com>

docs/documentation/upgrading/topics/changes/changes-25_0_0.adoc

@@ -88,3 +88,7 @@ Note that the `setSessionState()` method is also removed from the `IDToken` clas
 A new `Session State (session_state)` mapper is also included and can be assigned to client scopes (for instance `basic` client scope) to revert to the old behavior.
 
 If an old version of the JS adapter is used, the `Session State (session_state)` mapper should also be used via client scopes as described above.
+
+= Default `http-pool-max-threads` reduced
+
+`http-pool-max-threads` if left unset will default to the greater of 50 or 4 x (available processors). Previously it defaulted to the greater of 200 or 8 x (available processors). Reducing the number or task threads for most usage scenarios will result in slightly higher performance due to less context switching among active threads.

quarkus/config-api/src/main/java/org/keycloak/config/HttpOptions.java

@@ -127,9 +127,9 @@ public class HttpOptions {
     public static final Option<Integer> HTTP_POOL_MAX_THREADS = new OptionBuilder<>("http-pool-max-threads", Integer.class)
             .category(OptionCategory.HTTP)
             .description("The maximum number of threads. If this is not specified then it will be automatically sized " +
-                         "to the greatest of 8 * the number of available processors and 200. " +
+                         "to the greater of 4 * the number of available processors and 50. " +
-                         "For example if there are 4 processors the max threads will be 200. " +
+                         "For example if there are 4 processors the max threads will be 50. " +
-                         "If there are 48 processors it will be 384.")
+                         "If there are 48 processors it will be 192.")
             .build();
 
 }

quarkus/runtime/src/main/java/org/keycloak/quarkus/runtime/configuration/mappers/HttpPropertyMappers.java

@@ -20,6 +20,7 @@ import static java.util.Optional.of;
 import static org.keycloak.quarkus.runtime.configuration.mappers.PropertyMapper.fromOption;
 
 public final class HttpPropertyMappers {
+    private static final int MIN_MAX_THREADS = 50;
     private static final String QUARKUS_HTTPS_CERT_FILES = "quarkus.http.ssl.certificate.files";
     private static final String QUARKUS_HTTPS_CERT_KEY_FILES = "quarkus.http.ssl.certificate.key-files";
 
@@ -111,6 +112,7 @@ public final class HttpPropertyMappers {
                         .build(),
                 fromOption(HttpOptions.HTTP_POOL_MAX_THREADS)
                         .to("quarkus.thread-pool.max-threads")
+                        .transformer(HttpPropertyMappers::resolveMaxThreads)
                         .paramLabel("threads")
                         .build()
         };
@@ -178,5 +180,13 @@ public final class HttpPropertyMappers {
         }
         return value;
     }
+
+    private static Optional<String> resolveMaxThreads(Optional<String> value,
+            ConfigSourceInterceptorContext configSourceInterceptorContext) {
+        if (value.isEmpty()) {
+            return of(String.valueOf(Math.max(MIN_MAX_THREADS, 4 * Runtime.getRuntime().availableProcessors())));
+        }
+        return value;
+    }
 }
 

quarkus/tests/integration/src/test/resources/org/keycloak/it/cli/dist/approvals/cli/help/HelpCommandDistTest.testStartDevHelp.approved.txt

@@ -157,9 +157,9 @@ HTTP(S):
                        situation. Excess requests will return a "503 Server not Available" response.
 --http-pool-max-threads <threads>
                      The maximum number of threads. If this is not specified then it will be
-                       automatically sized to the greatest of 8 * the number of available
+                       automatically sized to the greater of 4 * the number of available processors
-                       processors and 200. For example if there are 4 processors the max threads
+                       and 50. For example if there are 4 processors the max threads will be 50. If
-                       will be 200. If there are 48 processors it will be 384.
+                       there are 48 processors it will be 192.
 --http-port <port>   The used HTTP port. Default: 8080.
 --http-relative-path <path>
                      Set the path relative to '/' for serving resources. The path must start with a

quarkus/tests/integration/src/test/resources/org/keycloak/it/cli/dist/approvals/cli/help/HelpCommandDistTest.testStartDevHelpAll.approved.txt

@@ -201,9 +201,9 @@ HTTP(S):
                        situation. Excess requests will return a "503 Server not Available" response.
 --http-pool-max-threads <threads>
                      The maximum number of threads. If this is not specified then it will be
-                       automatically sized to the greatest of 8 * the number of available
+                       automatically sized to the greater of 4 * the number of available processors
-                       processors and 200. For example if there are 4 processors the max threads
+                       and 50. For example if there are 4 processors the max threads will be 50. If
-                       will be 200. If there are 48 processors it will be 384.
+                       there are 48 processors it will be 192.
 --http-port <port>   The used HTTP port. Default: 8080.
 --http-relative-path <path>
                      Set the path relative to '/' for serving resources. The path must start with a

quarkus/tests/integration/src/test/resources/org/keycloak/it/cli/dist/approvals/cli/help/HelpCommandDistTest.testStartHelp.approved.txt

@@ -158,9 +158,9 @@ HTTP(S):
                        situation. Excess requests will return a "503 Server not Available" response.
 --http-pool-max-threads <threads>
                      The maximum number of threads. If this is not specified then it will be
-                       automatically sized to the greatest of 8 * the number of available
+                       automatically sized to the greater of 4 * the number of available processors
-                       processors and 200. For example if there are 4 processors the max threads
+                       and 50. For example if there are 4 processors the max threads will be 50. If
-                       will be 200. If there are 48 processors it will be 384.
+                       there are 48 processors it will be 192.
 --http-port <port>   The used HTTP port. Default: 8080.
 --http-relative-path <path>
                      Set the path relative to '/' for serving resources. The path must start with a

quarkus/tests/integration/src/test/resources/org/keycloak/it/cli/dist/approvals/cli/help/HelpCommandDistTest.testStartHelpAll.approved.txt

@@ -202,9 +202,9 @@ HTTP(S):
                        situation. Excess requests will return a "503 Server not Available" response.
 --http-pool-max-threads <threads>
                      The maximum number of threads. If this is not specified then it will be
-                       automatically sized to the greatest of 8 * the number of available
+                       automatically sized to the greater of 4 * the number of available processors
-                       processors and 200. For example if there are 4 processors the max threads
+                       and 50. For example if there are 4 processors the max threads will be 50. If
-                       will be 200. If there are 48 processors it will be 384.
+                       there are 48 processors it will be 192.
 --http-port <port>   The used HTTP port. Default: 8080.
 --http-relative-path <path>
                      Set the path relative to '/' for serving resources. The path must start with a

quarkus/tests/integration/src/test/resources/org/keycloak/it/cli/dist/approvals/cli/help/HelpCommandDistTest.testStartOptimizedHelp.approved.txt

@@ -131,9 +131,9 @@ HTTP(S):
                        situation. Excess requests will return a "503 Server not Available" response.
 --http-pool-max-threads <threads>
                      The maximum number of threads. If this is not specified then it will be
-                       automatically sized to the greatest of 8 * the number of available
+                       automatically sized to the greater of 4 * the number of available processors
-                       processors and 200. For example if there are 4 processors the max threads
+                       and 50. For example if there are 4 processors the max threads will be 50. If
-                       will be 200. If there are 48 processors it will be 384.
+                       there are 48 processors it will be 192.
 --http-port <port>   The used HTTP port. Default: 8080.
 --https-certificate-file <file>
                      The file path to a server certificate or certificate chain in PEM format.

quarkus/tests/integration/src/test/resources/org/keycloak/it/cli/dist/approvals/cli/help/HelpCommandDistTest.testStartOptimizedHelpAll.approved.txt

@@ -175,9 +175,9 @@ HTTP(S):
                        situation. Excess requests will return a "503 Server not Available" response.
 --http-pool-max-threads <threads>
                      The maximum number of threads. If this is not specified then it will be
-                       automatically sized to the greatest of 8 * the number of available
+                       automatically sized to the greater of 4 * the number of available processors
-                       processors and 200. For example if there are 4 processors the max threads
+                       and 50. For example if there are 4 processors the max threads will be 50. If
-                       will be 200. If there are 48 processors it will be 384.
+                       there are 48 processors it will be 192.
 --http-port <port>   The used HTTP port. Default: 8080.
 --https-certificate-file <file>
                      The file path to a server certificate or certificate chain in PEM format.