Fix CPU pin if clients don't shutdown() their socket properly.

If we haven't read any bytes yet, then we try a few times a few ms apart
to see if we get anything. If not, treat it as an EOF. Otherwise, read
bytes until we get an EOF or EAGAIN. EAGAIN after a consistent read of
bytes is treaded as an EOF immediately.

src/Json.c

@@ -25,6 +25,7 @@
 
 #include <Memory.h>
 #include <Str.h>
+#include <Util.h>
 
 #include <stdio.h>
 #include <stddef.h>
@@ -705,7 +706,12 @@ JsonFree(HashMap * object)
 static int
 JsonConsumeWhitespace(JsonParserState * state)
 {
+    static const int nRetries = 5;
+    static const int delay = 2;
+
     int c;
+    int tries = 0;
+    int readFlg = 0;
 
     while (1)
     {
@@ -721,7 +727,17 @@ JsonConsumeWhitespace(JsonParserState * state)
             if (errno == EAGAIN)
             {
                 clearerr(state->stream);
-                continue;
+                tries++;
+
+                if (tries >= nRetries || readFlg)
+                {
+                    break;
+                }
+                else
+                {
+                    UtilSleepMillis(delay);
+                    continue;
+                }
             }
             else
             {
@@ -729,6 +745,13 @@ JsonConsumeWhitespace(JsonParserState * state)
             }
         }
 
+        /* As soon as we've successfully read a byte, treat
+         * future EAGAINs as EOF, because some clients don't
+         * properly shutdown their sockets.
+         */
+        readFlg = 1;
+        tries = 0;
+
         if (!isspace(c))
         {
             break;