perl plugin: lock base thread interpreter in perl_init() too.

Avoid race conditions with c_ithread_create() called from threads of already-initialized plugins.
Fix for https://github.com/collectd/collectd/issues/1706.

diff --git a/src/perl.c b/src/perl.c
index 945e22586c806e2b3000f18c78e201cbbf74fff4..0b5debe67730ce99e218bde5a41461b51e16ec3d 100644 (file)
--- a/src/perl.c
+++ b/src/perl.c
@@ -1,4 +1,4 @@
-/**
+/*
  * collectd - src/perl.c
  * Copyright (C) 2007-2009  Sebastian Harl
  *
@@ -1911,6 +1911,7 @@ static XS (Collectd_call_by_name)
 
 static int perl_init (void)
 {
+       int status;
        dTHX;
 
        if (NULL == perl_threads)
@@ -1928,7 +1929,19 @@ static int perl_init (void)
 
        log_debug ("perl_init: c_ithread: interp = %p (active threads: %i)",
                        aTHX, perl_threads->number_of_threads);
-       return pplugin_call_all (aTHX_ PLUGIN_INIT);
+
+       /* Lock the base thread to avoid race conditions with c_ithread_create().
+        * See https://github.com/collectd/collectd/issues/9 and
+        *     https://github.com/collectd/collectd/issues/1706 for details. */
+
+       assert (aTHX == perl_threads->head->interp);
+       pthread_mutex_lock (&perl_threads->mutex);
+
+       status = pplugin_call_all (aTHX_ PLUGIN_INIT);
+
+       pthread_mutex_unlock (&perl_threads->mutex);
+
+       return status;
 } /* static int perl_init (void) */
 
 static int perl_read (void)