diff --git a/tracer/forward.c b/tracer/forward.c
index cfb837f9e5d7d82245f26ad08684cf43cc0ddd1f..b982a890275f2fc2251109e4796d14d5f3a0672c 100644
--- a/tracer/forward.c
+++ b/tracer/forward.c
@@ -5,13 +5,61 @@
 #include <arpa/inet.h>
 #include <unistd.h>
 #include <pthread.h>
+#include <string.h>
+
+typedef struct databuf {
+  char *d;
+  int l;
+  struct databuf *next;
+} databuf;
 
 typedef struct {
   int s;
   int sc;
   pthread_mutex_t lock;
+  pthread_mutex_t datalock;
+  pthread_cond_t datacond;
+  databuf * volatile head, *tail;
 } forward_data;
 
+static void *data_sender(void *_f)
+{
+  forward_data *f = _f;
+  databuf *cur;
+  char *buf, *b;
+  int size;
+
+wait:
+  if (pthread_mutex_lock(&f->datalock)) abort();
+  while (f->head == NULL)
+    if (pthread_cond_wait(&f->datacond, &f->datalock)) abort();
+  cur = f->head;
+  buf = cur->d;
+  size = cur->l;
+  f->head = cur->next;
+  if (f->head == NULL) f->tail = NULL;
+  if (pthread_mutex_unlock(&f->datalock)) abort();
+  free(cur);
+  goto process;
+
+process:
+  if (pthread_mutex_lock(&f->lock)) abort();
+
+  b = buf;
+  while (size) {
+    int l = write(f->s, b, size);
+    if (l <= 0) { printf("forward error\n"); exit(1); }
+    size -= l;
+    b += l;
+  }
+
+  if (pthread_mutex_unlock(&f->lock)) abort();
+
+  free(buf);
+
+  goto wait;
+}
+
 static void do_forward(forward_data *f, int from, int to, int lock)
 {
   int l, len;
@@ -66,6 +114,11 @@ void *forwarder(char *ip, int port)
   f = malloc(sizeof(*f)); if (f == NULL) abort();
 
   pthread_mutex_init(&f->lock, NULL);
+  pthread_mutex_init(&f->datalock, NULL);
+  pthread_cond_init(&f->datacond, NULL);
+
+  f->sc = -1;
+  f->head = f->tail = NULL;
 
   f->s = socket(AF_INET, SOCK_STREAM, 0);
   if (f->s == -1) { perror("socket"); exit(1); }
@@ -77,21 +130,27 @@ void *forwarder(char *ip, int port)
   if (connect(f->s, (struct sockaddr *)&a, sizeof(a)) == -1)
     { perror("connect"); exit(1); }
 
+  new_thread(data_sender, f);
+
   return f;
 }
 
 void forward(void *_forwarder, char *buf, int size)
 {
   forward_data *f = _forwarder;
+  databuf *new;
 
-  if (pthread_mutex_lock(&f->lock)) abort();
+  new = malloc(sizeof(*new)); if (new == NULL) abort();
 
-  while (size) {
-    int l = write(f->s, buf, size);
-    if (l <= 0) { printf("forward error\n"); exit(1); }
-    size -= l;
-    buf += l;
-  }
+  if (pthread_mutex_lock(&f->datalock)) abort();
 
-  if (pthread_mutex_unlock(&f->lock)) abort();
+  new->d = malloc(size); if (new->d == NULL) abort();
+  memcpy(new->d, buf, size);
+  new->l = size;
+  new->next = NULL;
+  if (f->head == NULL) f->head = new;
+  f->tail = new;
+
+  if (pthread_cond_signal(&f->datacond)) abort();
+  if (pthread_mutex_unlock(&f->datalock)) abort();
 }