lib: Free unused data stack memory once per second while running ioloop

This way if the data stack has grown excessively large temporarily, it
won't permanently waste memory. And if the data stack grows back to the
same large size, re-allocating it once per second doesn't cause performance
problems.

diff --git a/src/lib/ioloop.c b/src/lib/ioloop.c
index 39ef3a30179e034c3a186a01713330a74455c6f0..7ba0fb67233abcbb77dc82cf1612c397d71a4dba 100644 (file)
--- a/src/lib/ioloop.c
+++ b/src/lib/ioloop.c
@@ -19,6 +19,8 @@ static ARRAY(io_switch_callback_t *) io_switch_callbacks = ARRAY_INIT;
 static ARRAY(io_destroy_callback_t *) io_destroy_callbacks = ARRAY_INIT;
 static bool panic_on_leak = FALSE, panic_on_leak_set = FALSE;
 
+static time_t data_stack_last_free_unused = 0;
+
 static void io_loop_initialize_handler(struct ioloop *ioloop)
 {
        unsigned int initial_fd_count;
@@ -694,6 +696,17 @@ void io_loop_handle_timeouts(struct ioloop *ioloop)
        T_BEGIN {
                io_loop_handle_timeouts_real(ioloop);
        } T_END;
+
+       /* Free the unused memory in data stack once per second. This way if
+          the data stack has grown excessively large temporarily, it won't
+          permanently waste memory. And if the data stack grows back to the
+          same large size, re-allocating it once per second doesn't cause
+          performance problems. */
+       if (data_stack_last_free_unused != ioloop_time) {
+               if (data_stack_last_free_unused != 0)
+                       data_stack_free_unused();
+               data_stack_last_free_unused = ioloop_time;
+       }
 }
 
 void io_loop_call_io(struct io *io)