diff -ur Mail-SpamAssassin-2.51.orig/lib/Mail/SpamAssassin/Bayes.pm Mail-SpamAssassin-2.51/lib/Mail/SpamAssassin/Bayes.pm
--- Mail-SpamAssassin-2.51.orig/lib/Mail/SpamAssassin/Bayes.pm	Wed Mar 19 00:27:46 2003
+++ Mail-SpamAssassin-2.51/lib/Mail/SpamAssassin/Bayes.pm	Fri Mar 21 18:17:24 2003
@@ -41,6 +41,7 @@
   $MIN_SPAM_CORPUS_SIZE_FOR_BAYES
   $MIN_HAM_CORPUS_SIZE_FOR_BAYES
   %HEADER_NAME_COMPRESSION
+  $OPPORTUNISTIC_LOCK_VALID
 };
 
 @ISA = qw();
@@ -153,6 +154,9 @@
 $MIN_SPAM_CORPUS_SIZE_FOR_BAYES = 200;
 $MIN_HAM_CORPUS_SIZE_FOR_BAYES = 200;
 
+# How many seconds should the opportunistic_expire lock be valid?
+$OPPORTUNISTIC_LOCK_VALID = 300;
+
 # Should we use the Robinson f(w) equation from
 # http://radio.weblogs.com/0101454/stories/2002/09/16/spamDetection.html ?
 # It gives better results, in that scores are more likely to distribute
@@ -940,14 +944,7 @@
   $self->{store}->add_touches_to_journal();
   $self->{store}->scan_count_increment();
 
-  # handle expiry and journal syncing
-  if ($self->{store}->expiry_due()) {
-    dbg ("expiration is due: expiring old tokens now...");
-    $self->{store}->sync_journal();
-    $self->{store}->expire_old_tokens();
-    dbg ("expiration done");
-  }
-
+  $self->opportunistic_expire();
   $self->{store}->untie_db();
   return $score;
 
@@ -957,6 +954,22 @@
   return 0.5;           # nice and neutral
 }
 
+sub opportunistic_expire {
+  my($self) = @_;
+
+  # Is an expire or journal sync running?
+  my $running_expire = $self->{store}->get_running_expire_tok();
+  if ( defined $running_expire && $running_expire+$OPPORTUNISTIC_LOCK_VALID > time() ) { return; }
+
+  # handle expiry and journal syncing
+  if ($self->{store}->expiry_due()) {
+    dbg ("expiration is due: expiring old tokens now...");
+    $self->{store}->sync_journal();
+    $self->{store}->expire_old_tokens();
+    dbg ("expiration done");
+  }
+}
+
 ###########################################################################
 
 sub dbg { Mail::SpamAssassin::dbg (@_); }
diff -ur Mail-SpamAssassin-2.51.orig/lib/Mail/SpamAssassin/BayesStore.pm Mail-SpamAssassin-2.51/lib/Mail/SpamAssassin/BayesStore.pm
--- Mail-SpamAssassin-2.51.orig/lib/Mail/SpamAssassin/BayesStore.pm	Fri Mar 21 18:18:14 2003
+++ Mail-SpamAssassin-2.51/lib/Mail/SpamAssassin/BayesStore.pm	Fri Mar 21 18:27:16 2003
@@ -19,7 +19,7 @@
   @DBNAMES @DB_EXTENSIONS
   $NSPAM_MAGIC_TOKEN $NHAM_MAGIC_TOKEN $LAST_EXPIRE_MAGIC_TOKEN
   $NTOKENS_MAGIC_TOKEN $OLDEST_TOKEN_AGE_MAGIC_TOKEN
-  $SCANCOUNT_BASE_MAGIC_TOKEN 
+  $SCANCOUNT_BASE_MAGIC_TOKEN $RUNNING_EXPIRE_MAGIC_TOKEN
 };
 
 @ISA = qw();
@@ -66,6 +66,7 @@
 $LAST_EXPIRE_MAGIC_TOKEN = '**LASTEXPIRE';
 $NTOKENS_MAGIC_TOKEN = '**NTOKENS';
 $SCANCOUNT_BASE_MAGIC_TOKEN = '**SCANBASE';
+$RUNNING_EXPIRE_MAGIC_TOKEN = '**RUNNINGEXPIRE';
 
 use constant MAX_SIZE_FOR_SCAN_COUNT_FILE => 5000;
 
@@ -275,8 +276,13 @@
 sub expire_old_tokens_trapped {
   my ($self, $opts) = @_;
 
-  if (!$self->expiry_due() && !$self->{bayes}->{main}->{learn_force_expire})
-				{ return 0; }
+  # Flag that we're doing work
+  $self->set_running_expire_tok();
+
+  if (!$self->expiry_due() && !$self->{bayes}->{main}->{learn_force_expire}) {
+    $self->remove_running_expire_tok();
+    return 0;
+  }
 
   my $too_old = $self->scan_count_get();
   $too_old = ($too_old < $self->{expiry_count} ? 
@@ -316,7 +322,8 @@
 	  || $tok eq $LAST_EXPIRE_MAGIC_TOKEN
 	  || $tok eq $NTOKENS_MAGIC_TOKEN
 	  || $tok eq $OLDEST_TOKEN_AGE_MAGIC_TOKEN
-	  || $tok eq $SCANCOUNT_BASE_MAGIC_TOKEN);
+	  || $tok eq $SCANCOUNT_BASE_MAGIC_TOKEN
+	  || $tok eq $RUNNING_EXPIRE_MAGIC_TOKEN);
 
     my ($ts, $th, $atime) = $self->tok_get ($tok);
 
@@ -341,8 +348,9 @@
       }
     }
 
-    if ($showdots && (($kept + $deleted) % 1000) == 0) {
-      print STDERR ".";
+    if ((($kept + $deleted) % 1000) == 0) {
+      if ($showdots) { print STDERR "."; }
+      $self->set_running_expire_tok();
     }
   }
 
@@ -366,7 +374,7 @@
   @deleted_toks = ();		# free 'em up
   $deleted -= $reprieved;
 
-  # and add the magic tokens
+  # and add the magic tokens.  don't add the expire_running token.
   $new_toks{$SCANCOUNT_BASE_MAGIC_TOKEN} = $self->{db_toks}->{$SCANCOUNT_BASE_MAGIC_TOKEN};
   $new_toks{$LAST_EXPIRE_MAGIC_TOKEN} = $self->scan_count_get();
   $new_toks{$OLDEST_TOKEN_AGE_MAGIC_TOKEN} = $oldest;
@@ -388,10 +396,8 @@
     }
   }
 
-  # ok, once that's done we can re-tie.  Call untie_db() first so
-  # we unlock correctly etc. first
+  # Call untie_db() first so we unlock correctly etc. first
   $self->untie_db();
-  $self->tie_db_writable();
 
   my $done = time();
 
@@ -478,6 +484,21 @@
   ($ns || 0, $nn || 0);
 }
 
+sub get_running_expire_tok {
+  my ($self) = @_;
+  return $self->{db_toks}->{$RUNNING_EXPIRE_MAGIC_TOKEN};
+}
+
+sub set_running_expire_tok {
+  my ($self) = @_;
+  $self->{db_toks}->{$RUNNING_EXPIRE_MAGIC_TOKEN} = time();
+}
+
+sub remove_running_expire_tok {
+  my ($self) = @_;
+  delete $self->{db_toks}->{$RUNNING_EXPIRE_MAGIC_TOKEN};
+}
+
 ###########################################################################
 
 # db abstraction: allow deferred writes, since we will be frequently
@@ -561,7 +582,7 @@
   };
   my $err = $@;
 
-  # ok, untie from write-mode, delete the retired journal
+  # ok, untie from write-mode
   $self->untie_db();
 
   # handle any errors that may have occurred
@@ -576,6 +597,9 @@
 sub sync_journal_trapped {
   my ($self, $opts, $path) = @_;
 
+  # Flag that we're doing work
+  $self->set_running_expire_tok();
+
   my $started = time();
   my $count = 0;
   my $total_count = 0;
@@ -625,8 +649,9 @@
   while( my($k,$v) = each %tokens ) {
     $self->tok_touch_token ($v, $k);
 
-    if ($showdots && (++$count % 1000) == 0) {
-      print STDERR ".";
+    if ((++$count % 1000) == 0) {
+      if ($showdots) { print STDERR "."; }
+      $self->set_running_expire_tok();
     }
   }