new file mode 100644
--- /dev/null
+++ b/src/core/ngx_write_chain.c
@@ -0,0 +1,203 @@
+
+#include <ngx_config.h>
+
+#include <ngx_core.h>
+#include <ngx_types.h>
+#include <ngx_alloc.h>
+#include <ngx_array.h>
+#include <ngx_hunk.h>
+#include <ngx_connection.h>
+#include <ngx_sendv.h>
+#include <ngx_sendfile.h>
+
+#include <ngx_write_chain.h>
+
+
+ngx_chain_t *ngx_write_chain(ngx_connection_t *c, ngx_chain_t *in, off_t flush)
+{
+    int           rc, i, last;
+    u_int         flags;
+    char         *prev;
+    off_t         sent;
+    ngx_iovec_t  *iov;
+    ngx_array_t   header, trailer;
+    ngx_hunk_t   *file;
+    ngx_chain_t  *ce;
+
+    ch = in;
+    file = NULL;
+    last = 0;
+
+    ngx_init_array(header, c->pool, 10, sizeof(ngx_iovec_t), NGX_CHAIN_ERROR);
+    ngx_init_array(trailer, c->pool, 10, sizeof(ngx_iovec_t), NGX_CHAIN_ERROR);
+
+    do {
+        header.nelts = 0;
+        trailer.nelts = 0;
+
+        if (ce->hunk->type & NGX_HUNK_IN_MEMORY) {
+            prev = NULL;
+            iov = NULL;
+
+            /* create iovec and coalesce the neighbouring chain entries */
+            while (ce && (ce->hunk->type & NGX_HUNK_IN_MEMORY))
+            {
+                if (prev == ce->hunk->pos.mem) {
+                    iov->ngx_iov_len += ce->hunk->last.mem - ce->hunk->pos.mem;
+
+                } else {
+                    ngx_test_null(iov, ngx_push_array(&header),
+                                  NGX_CHAIN_ERROR);
+                    iov->ngx_iov_base = ce->hunk->pos.mem;
+                    iov->ngx_iov_len = ce->hunk->last.mem - ce->hunk->pos.mem;
+                    prev = ce->hunk->last.mem;
+                }
+
+                if (ce->hunk->type & NGX_HUNK_LAST) {
+                    last = 1;
+                }
+
+                ce = ce->next;
+            }
+        }
+
+        if (ce && (ce->hunk->type & NGX_HUNK_FILE)) {
+            file = ce->hunk;
+            ce = ce->next;
+
+            if (ce->hunk->type & NGX_HUNK_LAST) {
+                last = 1;
+            }
+        }
+
+#if (HAVE_MAX_SENDFILE_IOVEC)
+        if (file && header->nelts > HAVE_MAX_SENDFILE_IOVEC) {
+            rc = ngx_sendv(c->fd, (ngx_iovec_t *) header->elts, header->nelts,
+                           &sent);
+        } else {
+#endif
+            if (ch && ch->hunk->type & NGX_HUNK_IN_MEMORY) {
+                prev = NULL;
+                iov = NULL;
+
+                while (ch && (ch->hunk->type & NGX_HUNK_IN_MEMORY)) {
+
+                    if (prev == ch->hunk->pos.mem) {
+                        iov->ngx_iov_len +=
+                                        ch->hunk->last.mem - ch->hunk->pos.mem;
+
+                    } else {
+                        ngx_test_null(iov, ngx_push_array(trailer),
+                                      NGX_CHAIN_ERROR);
+                        iov->ngx_iov_base = ch->hunk->pos.mem;
+                        iov->ngx_iov_len =
+                                        ch->hunk->last.mem - ch->hunk->pos.mem;
+                        prev = ch->hunk->last.mem;
+                    }
+
+                    if (ch->hunk->type & NGX_HUNK_LAST) {
+                        last = 1;
+                    }
+
+                    ch = ch->next;
+                }
+            }
+
+            if (file) {
+                flags = ngx_sendfile_flags;
+#if (HAVE_SENDFILE_DISCONNECT)
+                if (last && c->close) {
+                    flags |= NGX_SENDFILE_DISCONNECT;
+                }
+#endif
+                rc = ngx_sendfile(c,
+                                  (ngx_iovec_t *) header->elts, header->nelts,
+                                  file->file->fd, file->pos.file,
+                                  (size_t) (file->last.file - file->pos.file),
+                                  (ngx_iovec_t *) trailer->elts, trailer->nelts,
+                                  &sent, flags);
+
+#if (HAVE_AIO_EVENT) && !(HAVE_IOCP_EVENT)
+            } else if (ngx_event_flags & NGX_HAVE_AIO_EVENT) {
+
+                sent = 0;
+                rc = NGX_AGAIN;
+                iov = (ngx_iovec_t *) header->elts;
+                for (i = 0; i < header->nelts; i++) {
+                    rc = ngx_event_aio_write(c, iov[i].ngx_iov_base,
+                                             iov[i].ngx_iov_len);
+
+                    if (rc > 0) {
+                        sent += rc;
+                    } else {
+                        break;
+                    }
+
+                    if (rc < (int) iov->ngx_iov_len) {
+                        break;
+                    }
+                }
+#endif
+            } else {
+                rc = ngx_sendv(c, (ngx_iovec_t *) header->elts, header->nelts);
+
+                sent = rc > 0 ? rc: 0;
+
+#if (NGX_DEBUG_EVENT_WRITE)
+                ngx_log_debug(c->log, "sendv: " OFF_FMT _ sent);
+#endif
+            }
+#if (HAVE_MAX_SENDFILE_IOVEC)
+        }
+#endif
+        if (rc == NGX_ERROR)
+            return (ngx_chain_t *) NGX_ERROR;
+
+        c->sent += sent;
+        flush -= sent;
+
+        for (ch = in; ch; ch = ch->next) {
+
+#if (NGX_DEBUG_EVENT_WRITE)
+            ngx_log_debug(c->log, "event write: %x " QX_FMT " " OFF_FMT _
+                          ch->hunk->type _
+                          ch->hunk->pos.file _
+                          ch->hunk->last.file - ch->hunk->pos.file);
+#endif
+
+            if (sent >= ch->hunk->last.file - ch->hunk->pos.file) {
+                sent -= ch->hunk->last.file - ch->hunk->pos.file;
+                ch->hunk->pos.file = ch->hunk->last.file;
+
+#if (NGX_DEBUG_EVENT_WRITE)
+                ngx_log_debug(c->log, "event write: " QX_FMT " 0 " OFF_FMT _
+                              ch->hunk->pos.file _ sent);
+#endif
+
+/*
+                if (ch->hunk->type & NGX_HUNK_LAST)
+                   break;
+*/
+
+                continue;
+            }
+
+            ch->hunk->pos.file += sent;
+
+#if (NGX_DEBUG_EVENT_WRITE)
+            ngx_log_debug(c->log, "event write: " QX_FMT " " OFF_FMT _
+                          ch->hunk->pos.file _
+                          ch->hunk->last.file - ch->hunk->pos.file);
+#endif
+
+            break;
+        }
+
+    /* flush hunks if threaded state */
+    } while (c->write->context && flush > 0);
+
+    ngx_destroy_array(&trailer);
+    ngx_destroy_array(&header);
+
+    return ch;
+}

--- a/src/http/ngx_http_output_filter.c
+++ b/src/http/ngx_http_output_filter.c
@@ -71,7 +71,7 @@ int ngx_http_output_filter(ngx_http_requ
 {
     int                             rc;
     size_t                          size;
-    ngx_chain_t                    *ce, *pe;
+    ngx_chain_t                    *ce, *le;
     ngx_http_output_filter_ctx_t   *ctx;
     ngx_http_output_filter_conf_t  *conf;
 
@@ -96,7 +96,6 @@ int ngx_http_output_filter(ngx_http_requ
         if (!need_to_copy(r, hunk)) {
             ctx->out.hunk = hunk;
             ctx->out.next = NULL;
-
             return next_filter(r, &ctx->out);
         }
     }
@@ -105,17 +104,14 @@ int ngx_http_output_filter(ngx_http_requ
     if (hunk) {
 
         /* the output of the only hunk is common case so we have
-           special chain entry ctx->in for it */
+           the special chain entry ctx->in for it */
         if (ctx->incoming == NULL) {
             ctx->in.hunk = hunk;
             ctx->in.next = NULL;
             ctx->incoming = &ctx->in;
 
         } else {
-            for (ce = ctx->incoming; ce->next; ce = ce->next) {
-                /* void */ ;
-            }
-
+            for (ce = ctx->incoming; ce->next; ce = ce->next) { /* void */ ; }
             ngx_add_hunk_to_chain(ce->next, hunk, r->pool, NGX_ERROR);
         }
     }
@@ -124,8 +120,8 @@ int ngx_http_output_filter(ngx_http_requ
     if (ctx->hunk == NULL) {
 
         conf = (ngx_http_output_filter_conf_t *)
-               ngx_http_get_module_loc_conf(r->main ? r->main : r,
-                                            ngx_http_output_filter_module);
+                   ngx_http_get_module_loc_conf(r->main ? r->main : r,
+                                                ngx_http_output_filter_module);
 
         if (hunk->type & NGX_HUNK_LAST) {
             size = hunk->last.mem - hunk->pos.mem;
@@ -140,7 +136,6 @@ int ngx_http_output_filter(ngx_http_requ
         ngx_test_null(ctx->hunk,
                       ngx_create_temp_hunk(r->pool, size, 50, 50),
                       NGX_ERROR);
-
         ctx->hunk->type |= NGX_HUNK_RECYCLED;
 
 
@@ -153,13 +148,12 @@ int ngx_http_output_filter(ngx_http_requ
         }
 
         /* NGX_OK */
-
         /* set our hunk free */
         ctx->hunk->pos.mem = ctx->hunk->last.mem = ctx->hunk->start;
     }
 
 #if (NGX_SUPPRESS_WARN)
-    pe = NULL;
+    le = NULL;
 #endif
 
     /* process the chain ctx->incoming */
@@ -169,7 +163,7 @@ int ngx_http_output_filter(ngx_http_requ
             if (need_to_copy(r, ce->hunk)) {
                 break;
             }
-            pe = ce;
+            le = ce;
         }
 
         /* ... and pass them to the next filter */
@@ -178,10 +172,9 @@ int ngx_http_output_filter(ngx_http_requ
             ctx->out.hunk = ctx->incoming->hunk;
             ctx->out.next = ctx->incoming->next;
             ctx->incoming = ce;
-            pe->next = NULL;
+            le->next = NULL;
 
             rc = next_filter(r, &ctx->out);
-
             if (rc == NGX_ERROR || rc == NGX_AGAIN) {
                 return rc;
             }
@@ -197,29 +190,24 @@ int ngx_http_output_filter(ngx_http_requ
         do {
             rc = ngx_http_output_filter_copy_hunk(ctx->hunk,
                                                   ctx->incoming->hunk);
-
             if (rc == NGX_ERROR) {
                 return rc;
             }
 
 #if (NGX_FILE_AIO_READ)
-
             if (rc == NGX_AGAIN) {
                 return rc;
             }
-
 #endif
             ctx->out.hunk = ctx->hunk;
             ctx->out.next = NULL;
 
             rc = next_filter(r, &ctx->out);
-
             if (rc == NGX_ERROR || rc == NGX_AGAIN) {
                 return rc;
             }
 
             /* NGX_OK */
-
             /* set our hunk free */
             ctx->hunk->pos.mem = ctx->hunk->last.mem = ctx->hunk->start;
 
@@ -254,11 +242,9 @@ static int ngx_http_output_filter_copy_h
         }
 
 #if (NGX_FILE_AIO_READ)
-
         if (n == NGX_AGAIN) {
             return n;
         }
-
 #endif
 
         if (n != size) {
@@ -275,7 +261,6 @@ static int ngx_http_output_filter_copy_h
 
     } else {
         ngx_memcpy(src->pos.mem, dst->pos.mem, size);
-
         src->pos.mem += size;
         dst->last.mem += size;
     }