diff --git a/src/shrpx_client_handler.cc b/src/shrpx_client_handler.cc
index dc904fc8..4966726f 100644
--- a/src/shrpx_client_handler.cc
+++ b/src/shrpx_client_handler.cc
@@ -60,7 +60,7 @@ void upstream_writecb(bufferevent *bev, void *arg)
 {
   auto handler = reinterpret_cast<ClientHandler*>(arg);
   // We actually depend on write low-warter mark == 0.
-  if(handler->get_pending_write_length() > 0) {
+  if(handler->get_outbuf_length() > 0) {
     // Possibly because of deferred callback, we may get this callback
     // when the output buffer is not empty.
     return;
@@ -449,7 +449,7 @@ DownstreamConnection* ClientHandler::get_downstream_connection()
   }
 }
 
-size_t ClientHandler::get_pending_write_length()
+size_t ClientHandler::get_outbuf_length()
 {
   auto underlying = bufferevent_get_underlying(bev_);
   auto len = evbuffer_get_length(bufferevent_get_output(bev_));
diff --git a/src/shrpx_client_handler.h b/src/shrpx_client_handler.h
index bc76a48f..7e26277f 100644
--- a/src/shrpx_client_handler.h
+++ b/src/shrpx_client_handler.h
@@ -61,7 +61,7 @@ public:
   void pool_downstream_connection(DownstreamConnection *dconn);
   void remove_downstream_connection(DownstreamConnection *dconn);
   DownstreamConnection* get_downstream_connection();
-  size_t get_pending_write_length();
+  size_t get_outbuf_length();
   SSL* get_ssl() const;
   void set_http2_session(Http2Session *http2session);
   Http2Session* get_http2_session() const;
diff --git a/src/shrpx_http2_upstream.cc b/src/shrpx_http2_upstream.cc
index 227c501c..54a26be8 100644
--- a/src/shrpx_http2_upstream.cc
+++ b/src/shrpx_http2_upstream.cc
@@ -45,7 +45,7 @@ using namespace nghttp2;
 namespace shrpx {
 
 namespace {
-const size_t SHRPX_HTTP2_UPSTREAM_OUTPUT_UPPER_THRES = 64*1024;
+const size_t OUTBUF_MAX_THRES = 64*1024;
 } // namespace
 
 namespace {
@@ -59,8 +59,7 @@ ssize_t send_callback(nghttp2_session *session,
   auto bev = handler->get_bev();
   auto output = bufferevent_get_output(bev);
   // Check buffer length and return WOULDBLOCK if it is large enough.
-  if(handler->get_pending_write_length() >
-     SHRPX_HTTP2_UPSTREAM_OUTPUT_UPPER_THRES) {
+  if(handler->get_outbuf_length() > OUTBUF_MAX_THRES) {
     return NGHTTP2_ERR_WOULDBLOCK;
   }
 
@@ -595,7 +594,7 @@ int Http2Upstream::on_read()
   }
   if(nghttp2_session_want_read(session_) == 0 &&
      nghttp2_session_want_write(session_) == 0 &&
-     handler_->get_pending_write_length() == 0) {
+     handler_->get_outbuf_length() == 0) {
     if(LOG_ENABLED(INFO)) {
       ULOG(INFO, this) << "No more read/write for this HTTP2 session";
     }
@@ -620,7 +619,7 @@ int Http2Upstream::send()
   if(rv == 0) {
     if(nghttp2_session_want_read(session_) == 0 &&
        nghttp2_session_want_write(session_) == 0 &&
-       handler_->get_pending_write_length() == 0) {
+       handler_->get_outbuf_length() == 0) {
       if(LOG_ENABLED(INFO)) {
         ULOG(INFO, this) << "No more read/write for this HTTP2 session";
       }
@@ -907,8 +906,8 @@ ssize_t downstream_data_read_callback(nghttp2_session *session,
   // Send WINDOW_UPDATE before buffer is empty to avoid delay because
   // of RTT.
   if(*eof != 1 &&
-     handler->get_pending_write_length() + evbuffer_get_length(body) <
-     SHRPX_HTTP2_UPSTREAM_OUTPUT_UPPER_THRES) {
+     handler->get_outbuf_length() + evbuffer_get_length(body) <
+     OUTBUF_MAX_THRES) {
     if(downstream->resume_read(SHRPX_NO_BUFFER) != 0) {
       return NGHTTP2_ERR_CALLBACK_FAILURE;
     }
@@ -1086,9 +1085,9 @@ int Http2Upstream::on_downstream_body(Downstream *downstream,
   }
   nghttp2_session_resume_data(session_, downstream->get_stream_id());
 
-  auto outbuflen = handler->get_pending_write_length() +
+  auto outbuflen = handler->get_outbuf_length() +
     evbuffer_get_length(body);
-  if(outbuflen > SHRPX_HTTP2_UPSTREAM_OUTPUT_UPPER_THRES) {
+  if(outbuflen > OUTBUF_MAX_THRES) {
     downstream->pause_read(SHRPX_NO_BUFFER);
   }
 
diff --git a/src/shrpx_https_upstream.cc b/src/shrpx_https_upstream.cc
index 2c573558..ad2d678b 100644
--- a/src/shrpx_https_upstream.cc
+++ b/src/shrpx_https_upstream.cc
@@ -44,7 +44,7 @@ using namespace nghttp2;
 namespace shrpx {
 
 namespace {
-const size_t SHRPX_HTTPS_UPSTREAM_OUTPUT_UPPER_THRES = 64*1024;
+const size_t OUTBUF_MAX_THRES = 64*1024;
 const size_t SHRPX_HTTPS_MAX_HEADER_LENGTH = 64*1024;
 } // namespace
 
@@ -414,7 +414,7 @@ void https_downstream_readcb(bufferevent *bev, void *ptr)
       auto handler = upstream->get_client_handler();
       if(downstream->get_request_state() == Downstream::MSG_COMPLETE) {
         if(handler->get_should_close_after_write() &&
-           handler->get_pending_write_length() == 0) {
+           handler->get_outbuf_length() == 0) {
           // If all upstream response body has already written out to
           // the peer, we cannot use writecb for ClientHandler. In
           // this case, we just delete handler here.
@@ -435,7 +435,7 @@ void https_downstream_readcb(bufferevent *bev, void *ptr)
         // https_downstream_eventcb.
         //
         // Tunneled connection always indicates connection close.
-        if(handler->get_pending_write_length() == 0) {
+        if(handler->get_outbuf_length() == 0) {
           // For tunneled connection, if there is no pending data,
           // delete handler because on_write will not be called.
           delete handler;
@@ -446,8 +446,8 @@ void https_downstream_readcb(bufferevent *bev, void *ptr)
         }
       }
     } else {
-      if(upstream->get_client_handler()->get_pending_write_length() >
-         SHRPX_HTTPS_UPSTREAM_OUTPUT_UPPER_THRES) {
+      if(upstream->get_client_handler()->get_outbuf_length() >
+         OUTBUF_MAX_THRES) {
         downstream->pause_read(SHRPX_NO_BUFFER);
       }
     }
@@ -514,7 +514,7 @@ void https_downstream_eventcb(bufferevent *bev, short events, void *ptr)
 
       auto handler = upstream->get_client_handler();
       if(handler->get_should_close_after_write() &&
-         handler->get_pending_write_length() == 0) {
+         handler->get_outbuf_length() == 0) {
         // If all upstream response body has already written out to
         // the peer, we cannot use writecb for ClientHandler. In this
         // case, we just delete handler here.
diff --git a/src/shrpx_spdy_upstream.cc b/src/shrpx_spdy_upstream.cc
index 121849ae..903f13c8 100644
--- a/src/shrpx_spdy_upstream.cc
+++ b/src/shrpx_spdy_upstream.cc
@@ -45,7 +45,7 @@ using namespace nghttp2;
 namespace shrpx {
 
 namespace {
-const size_t SHRPX_SPDY_UPSTREAM_OUTPUT_UPPER_THRES = 64*1024;
+const size_t OUTBUF_MAX_THRES = 64*1024;
 } // namespace
 
 namespace {
@@ -59,8 +59,7 @@ ssize_t send_callback(spdylay_session *session,
   auto bev = handler->get_bev();
   auto output = bufferevent_get_output(bev);
   // Check buffer length and return WOULDBLOCK if it is large enough.
-  if(handler->get_pending_write_length() >
-     SHRPX_SPDY_UPSTREAM_OUTPUT_UPPER_THRES) {
+  if(handler->get_outbuf_length() > OUTBUF_MAX_THRES) {
     return SPDYLAY_ERR_WOULDBLOCK;
   }
 
@@ -452,7 +451,7 @@ int SpdyUpstream::on_read()
   if(rv == 0) {
     if(spdylay_session_want_read(session_) == 0 &&
        spdylay_session_want_write(session_) == 0 &&
-       handler_->get_pending_write_length() == 0) {
+       handler_->get_outbuf_length() == 0) {
       if(LOG_ENABLED(INFO)) {
         ULOG(INFO, this) << "No more read/write for this SPDY session";
       }
@@ -478,7 +477,7 @@ int SpdyUpstream::send()
   if(rv == 0) {
     if(spdylay_session_want_read(session_) == 0 &&
        spdylay_session_want_write(session_) == 0 &&
-       handler_->get_pending_write_length() == 0) {
+       handler_->get_outbuf_length() == 0) {
       if(LOG_ENABLED(INFO)) {
         ULOG(INFO, this) << "No more read/write for this SPDY session";
       }
@@ -751,8 +750,8 @@ ssize_t spdy_data_read_callback(spdylay_session *session,
   // Send WINDOW_UPDATE before buffer is empty to avoid delay because
   // of RTT.
   if(*eof != 1 &&
-     handler->get_pending_write_length() + evbuffer_get_length(body) <
-     SHRPX_SPDY_UPSTREAM_OUTPUT_UPPER_THRES) {
+     handler->get_outbuf_length() + evbuffer_get_length(body) <
+     OUTBUF_MAX_THRES) {
     if(downstream->resume_read(SHRPX_NO_BUFFER) != 0) {
       return SPDYLAY_ERR_CALLBACK_FAILURE;
     }
@@ -931,9 +930,9 @@ int SpdyUpstream::on_downstream_body(Downstream *downstream,
   }
   spdylay_session_resume_data(session_, downstream->get_stream_id());
 
-  auto outbuflen = upstream->get_client_handler()->get_pending_write_length() +
+  auto outbuflen = upstream->get_client_handler()->get_outbuf_length() +
     evbuffer_get_length(body);
-  if(outbuflen > SHRPX_SPDY_UPSTREAM_OUTPUT_UPPER_THRES) {
+  if(outbuflen > OUTBUF_MAX_THRES) {
     downstream->pause_read(SHRPX_NO_BUFFER);
   }