From d5ee9d24479887301c8f4d4a7ac1340fc7e712db Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20Sur=C3=BD?= <ondrej@isc.org>
Date: Wed, 1 Feb 2023 09:42:05 +0100
Subject: [PATCH] Bump the recursive-clients default to 1000000

Increase the default value of recursive-clients to one million.  The
server can handle this just fine, and we need to avoid the situation
where too many clients are stuck on the unresponsive fetches.
---
 bin/named/config.c    |  2 +-
 bin/named/server.c    | 16 +++-------------
 doc/arm/reference.rst | 13 +++++++------
 3 files changed, 11 insertions(+), 20 deletions(-)

diff --git a/bin/named/config.c b/bin/named/config.c
index 470d36cb71..3d33d917c5 100644
--- a/bin/named/config.c
+++ b/bin/named/config.c
@@ -99,7 +99,7 @@ options {\n\
 			    "\
 	prefetch 2 9;\n\
 	recursing-file \"named.recursing\";\n\
-	recursive-clients 1000;\n\
+	recursive-clients 100000;\n\
 	request-nsid false;\n\
 	reserved-sockets 512;\n\
 	resolver-query-timeout 10;\n\
diff --git a/bin/named/server.c b/bin/named/server.c
index bce0fab354..c4041b1e48 100644
--- a/bin/named/server.c
+++ b/bin/named/server.c
@@ -8586,19 +8586,9 @@ load_configuration(const char *filename, named_server_t *server,
 	configure_server_quota(maps, "update-quota", &server->sctx->updquota);
 
 	max = isc_quota_getmax(&server->sctx->recursionquota);
-	if (max > 1000) {
-		unsigned int margin = ISC_MAX(100, named_g_cpus + 1);
-		if (margin + 100 > max) {
-			isc_log_write(named_g_lctx, NAMED_LOGCATEGORY_GENERAL,
-				      NAMED_LOGMODULE_SERVER, ISC_LOG_ERROR,
-				      "'recursive-clients %d' too low when "
-				      "running with %d worker threads",
-				      max, named_g_cpus);
-			result = ISC_R_RANGE;
-
-			goto cleanup_bindkeys_parser;
-		}
-		softquota = max - margin;
+	if (max < 1000) {
+		isc_quota_max(&server->sctx->recursionquota, 1000);
+		softquota = 900;
 	} else {
 		softquota = (max * 90) / 100;
 	}
diff --git a/doc/arm/reference.rst b/doc/arm/reference.rst
index 8b5fa974ba..665bfd154f 100644
--- a/doc/arm/reference.rst
+++ b/doc/arm/reference.rst
@@ -3641,9 +3641,12 @@ system.
    :tags: query
    :short: Specifies the maximum number of concurrent recursive queries the server can perform.
 
-   This sets the maximum number (a "hard quota") of simultaneous recursive lookups
-   the server performs on behalf of clients. The default is
-   ``1000``. Because each recursing client uses a fair bit of memory (on
+   This sets the maximum number (a "hard quota") of simultaneous recursive
+   lookups the server performs on behalf of clients. The default is ``1000000``
+   (one million).  The minimum is ``1000``. Values below the minimum are
+   adjusted to the minimum value.
+
+   Because each recursing client uses a fair bit of memory (on
    the order of 20 kilobytes), the value of the :any:`recursive-clients`
    option may have to be decreased on hosts with limited memory.
 
@@ -3654,9 +3657,7 @@ system.
 
    A "soft quota" is also set. When this lower quota is exceeded,
    incoming requests are accepted, but for each one, a pending request
-   is dropped. If :any:`recursive-clients` is greater than 1000, the
-   soft quota is set to :any:`recursive-clients` minus 100; otherwise it is
-   set to 90% of :any:`recursive-clients`.
+   is dropped. The soft quota is set to 90% of :any:`recursive-clients`.
 
 .. namedconf:statement:: tcp-clients
    :tags: server