From 8549a8ea8fd2f1f7a64772bac35db839c9ed6618 Mon Sep 17 00:00:00 2001
From: "thek@adventure.(none)" <>
Date: Wed, 31 Oct 2007 12:25:18 +0100
Subject: [PATCH] Bug#31347 Increase in memory usage after many DROP USER
 statements

Dropping users causes huge increase in memory usage because field values were
allocated on the server memory root for temporary usage but never deallocated.

This patch changes the target memory root to be that of the thread handler
instead since this root is cleared between each statement.
---
 sql/sql_acl.cc | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/sql/sql_acl.cc b/sql/sql_acl.cc
index 6bc6cce5e72..d03aacd7f07 100644
--- a/sql/sql_acl.cc
+++ b/sql/sql_acl.cc
@@ -311,7 +311,7 @@ static my_bool acl_load(THD *thd, TABLE_LIST *tables)
       continue;
     }
 
-    const char *password= get_field(&mem, table->field[2]);
+    const char *password= get_field(thd->mem_root, table->field[2]);
     uint password_len= password ? strlen(password) : 0;
     set_user_salt(&user, password, password_len);
     if (user.salt_len == 0 && password_len != 0)
@@ -364,7 +364,7 @@ static my_bool acl_load(THD *thd, TABLE_LIST *tables)
       /* Starting from 4.0.2 we have more fields */
       if (table->s->fields >= 31)
       {
-        char *ssl_type=get_field(&mem, table->field[next_field++]);
+        char *ssl_type=get_field(thd->mem_root, table->field[next_field++]);
         if (!ssl_type)
           user.ssl_type=SSL_TYPE_NONE;
         else if (!strcmp(ssl_type, "ANY"))
@@ -378,11 +378,11 @@ static my_bool acl_load(THD *thd, TABLE_LIST *tables)
         user.x509_issuer=  get_field(&mem, table->field[next_field++]);
         user.x509_subject= get_field(&mem, table->field[next_field++]);
 
-        char *ptr = get_field(&mem, table->field[next_field++]);
+        char *ptr = get_field(thd->mem_root, table->field[next_field++]);
         user.user_resource.questions=ptr ? atoi(ptr) : 0;
-        ptr = get_field(&mem, table->field[next_field++]);
+        ptr = get_field(thd->mem_root, table->field[next_field++]);
         user.user_resource.updates=ptr ? atoi(ptr) : 0;
-        ptr = get_field(&mem, table->field[next_field++]);
+        ptr = get_field(thd->mem_root, table->field[next_field++]);
         user.user_resource.conn_per_hour= ptr ? atoi(ptr) : 0;
         if (user.user_resource.questions || user.user_resource.updates ||
             user.user_resource.conn_per_hour)
@@ -391,7 +391,7 @@ static my_bool acl_load(THD *thd, TABLE_LIST *tables)
         if (table->s->fields >= 36)
         {
           /* Starting from 5.0.3 we have max_user_connections field */
-          ptr= get_field(&mem, table->field[next_field++]);
+          ptr= get_field(thd->mem_root, table->field[next_field++]);
           user.user_resource.user_conn= ptr ? atoi(ptr) : 0;
         }
         else
@@ -4865,6 +4865,7 @@ static int handle_grant_table(TABLE_LIST *tables, uint table_no, bool drop,
   byte user_key[MAX_KEY_LENGTH];
   uint key_prefix_length;
   DBUG_ENTER("handle_grant_table");
+  THD *thd= current_thd;
 
   if (! table_no) // mysql.user table
   {
@@ -4932,17 +4933,18 @@ static int handle_grant_table(TABLE_LIST *tables, uint table_no, bool drop,
           DBUG_PRINT("info",("scan error: %d", error));
           continue;
         }
-        if (! (host= get_field(&mem, host_field)))
+        if (! (host= get_field(thd->mem_root, host_field)))
           host= "";
-        if (! (user= get_field(&mem, user_field)))
+        if (! (user= get_field(thd->mem_root, user_field)))
           user= "";
 
 #ifdef EXTRA_DEBUG
         DBUG_PRINT("loop",("scan fields: '%s'@'%s' '%s' '%s' '%s'",
                            user, host,
-                           get_field(&mem, table->field[1]) /*db*/,
-                           get_field(&mem, table->field[3]) /*table*/,
-                           get_field(&mem, table->field[4]) /*column*/));
+                           get_field(thd->mem_root, table->field[1]) /*db*/,
+                           get_field(thd->mem_root, table->field[3]) /*table*/,
+                           get_field(thd->mem_root,
+                                     table->field[4]) /*column*/));
 #endif
         if (strcmp(user_str, user) ||
             my_strcasecmp(system_charset_info, host_str, host))