Free memory of large lexical variables when leaving scope

diff --git a/scope.c b/scope.c
index 2fdea90..3ca31aa 100644 (file)
--- a/scope.c
+++ b/scope.c
@@ -15,6 +15,12 @@
 #include "EXTERN.h"
 #include "perl.h"
 
+/*
+ * This value determines how small an SV is "small enough" to keep
+ * in a lexical variable in anticipation of the next invocation.
+ */
+#define PADVAL_SMALL_ENOUGH 240
+
 SV**
 stack_grow(sp, p, n)
 SV** sp;
@@ -550,19 +556,33 @@ I32 base;
                case SVt_NULL:
                    break;
                case SVt_PVAV:
-                   av_clear((AV*)sv);
+                   if (AvMAX(sv) < (PADVAL_SMALL_ENOUGH / sizeof(SV*)))
+                       av_clear((AV*)sv);
+                   else
+                       av_undef((AV*)sv);
                    break;
                case SVt_PVHV:
-                   hv_clear((HV*)sv);
+                   if (HvMAX(sv) < (PADVAL_SMALL_ENOUGH / sizeof(SV*)))
+                       hv_clear((HV*)sv);
+                   else
+                       hv_undef((HV*)sv);
                    break;
                case SVt_PVCV:
-                   sub_generation++;
-                   cv_undef((CV*)sv);
+                   croak("panic: leave_scope pad code");
+               case SVt_RV:
+               case SVt_IV:
+               case SVt_NV:
+                   (void)SvOK_off(sv);
                    break;
                default:
-                   if (SvPOK(sv) && SvLEN(sv))
-                       (void)SvOOK_off(sv);
                    (void)SvOK_off(sv);
+                   (void)SvOOK_off(sv);
+                   if (SvPVX(sv) && SvLEN(sv) > PADVAL_SMALL_ENOUGH) {
+                       Safefree(SvPVX(sv));
+                       SvPVX(sv) = Nullch;
+                       SvLEN(sv) = 0;
+                       SvCUR(sv) = 0;
+                   }
                    break;
                }
            }