If anyone is trying to use the patched copy of xtend-1.2beta4 on the
heyu web site, you've probably run into the cpu loop problem.  I used
to kill xtend every hour or two (via script).  I finally straced out
the problem.  The following patch applied to the util.c file (in the
patched copy of xtend-1.2beta4 at the heyu web site) has worked
flawlessly and run continuously for a couple of weeks without a single
cpu loop.

--- xtend-1.2beta4.local/util.c 2000-05-27 17:17:21.000000000 -0400
+++ mace-xtend-patch/util.c 2003-04-11 21:57:54.000000000 -0400
@@ -80,8 +80,12 @@
void
getbytes (int fd, char *buf, int count)
{
+  fd_set zero;
+  struct timeval timeout;
   ssize_t bytes = 0, index = 0;

+  FD_ZERO (&zero);
+
   if (verbose > 8)
     printf ("Getting a message of %d (0x%X) bytes\n", count, count);

@@ -90,6 +94,24 @@
     {
       bytes = read (fd, &buf[index], count - index);
       index += bytes;
+
+      /* this is arguably foolish, but how else can one
+         handle receiving an EOF continually?
+         It only happens when using a heyu file (of course),
+         and actually is how 'tail(1)' handles the same thing. */
+
+      timeout.tv_sec = HEYU_TIMEOUT;
+      timeout.tv_usec = 100000;
+
+      if (bytes == 0 && select (0, &zero, &zero, &zero, &timeout) == -1)
+ {
+   if (errno == EINTR)
+     return;
+
+   fprintf (stderr, "select-timeout: %s\n", strerror (errno));
+   exit (-1);
+ }
+
     }
   alarm(0);
}
@@ -141,7 +163,7 @@
          and actually is how 'tail(1)' handles the same thing. */

       timeout.tv_sec = HEYU_TIMEOUT;
-      timeout.tv_usec = 0;
+      timeout.tv_usec = 100000;

       if (bytes == 0 && select (0, &zero, &zero, &zero, &timeout) == -1)
{
@@ -196,13 +218,35 @@
int
getmessage (int fd, char *buf)
{
+  fd_set zero;
+  struct timeval timeout;
   int bytes = 0;
   char count;

+  FD_ZERO (&zero);
+
   /* get the number of bytes we need to pull in */
   while (bytes == 0)
     {
       alarm(3);
+
+      /* this is arguably foolish, but how else can one
+         handle receiving an EOF continually?
+         It only happens when using a heyu file (of course),
+         and actually is how 'tail(1)' handles the same thing. */
+
+      timeout.tv_sec = HEYU_TIMEOUT;
+      timeout.tv_usec = 100000;
+
+      if (bytes == 0 && select (0, &zero, &zero, &zero, &timeout) == -1)
+ {
+   if (errno == EINTR)
+     return 0;
+
+   fprintf (stderr, "select-timeout: %s\n", strerror (errno));
+   exit (-1);
+ }
+
       bytes = read (fd, &count, 1);
       alarm(1);
     }