diff --git a/include/boost/fiber/condition.hpp b/include/boost/fiber/condition.hpp
index 6fb23e6e..7530c09a 100644
--- a/include/boost/fiber/condition.hpp
+++ b/include/boost/fiber/condition.hpp
@@ -39,10 +39,10 @@ enum class cv_status {
 
 class BOOST_FIBERS_DECL condition {
 private:
-    typedef detail::wait_queue< context >   wqueue_t;
+    typedef detail::wait_queue< context >   wait_queue_t;
 
     detail::spinlock        splk_;
-    wqueue_t                waiting_;
+    wait_queue_t                wait_queue_;
 
 public:
     condition();
@@ -73,7 +73,7 @@ public:
             // store this fiber in waiting-queue
             // in order notify (resume) this fiber later
             BOOST_ASSERT( ! f->wait_is_linked() );
-            waiting_.push_back( * f);
+            wait_queue_.push_back( * f);
 
             // unlock external
             lt.unlock();
@@ -87,7 +87,7 @@ public:
             lt.lock();
         } catch (...) {
             detail::spinlock_lock lk( splk_);
-            detail::erase_and_dispose( waiting_, f);
+            f->wait_unlink();
             throw;
         }
     }
@@ -104,7 +104,7 @@ public:
             // store this fiber in waiting-queue
             // in order notify (resume) this fiber later
             BOOST_ASSERT( ! f->wait_is_linked() );
-            waiting_.push_back( * f);
+            wait_queue_.push_back( * f);
 
             // unlock external
             lt.unlock();
@@ -116,7 +116,7 @@ public:
                 // this fiber was not notified before timeout
                 // lock spinlock again
                 detail::spinlock_lock lk( splk_);
-                detail::erase_and_dispose( waiting_, f);
+                f->wait_unlink();
 
                 status = cv_status::timeout;
             }
@@ -125,7 +125,7 @@ public:
             lt.lock();
         } catch (...) {
             detail::spinlock_lock lk( splk_);
-            detail::erase_and_dispose( waiting_, f);
+            f->wait_unlink();
             throw;
         }
 
diff --git a/include/boost/fiber/context.hpp b/include/boost/fiber/context.hpp
index b5c125c4..9820d945 100644
--- a/include/boost/fiber/context.hpp
+++ b/include/boost/fiber/context.hpp
@@ -43,9 +43,7 @@ class fiber_properties;
 class scheduler;
 struct sched_algorithm;
 
-class BOOST_FIBERS_DECL context : public detail::state_hook,
-                                  public detail::yield_hook,
-                                  public detail::wait_hook {
+class BOOST_FIBERS_DECL context {
 private:
     enum class fiber_status {
         ready = 0,
@@ -99,7 +97,7 @@ private:
     scheduler                               *   scheduler_;
     boost::context::execution_context           ctx_;
     fss_data_t                                  fss_data_;
-    std::vector< context * >                    waiting_;
+    std::vector< context * >                    wait_queue_;
     std::exception_ptr                          except_;
     std::chrono::steady_clock::time_point       tp_;
     fiber_properties                        *   properties_;
@@ -168,6 +166,11 @@ public:
         }
     };
 
+    detail::runnable_hook   runnable_hook_;
+    detail::ready_hook      ready_hook_;
+    detail::sleep_hook      sleep_hook_;
+    detail::wait_hook       wait_hook_;
+
     static context * active() noexcept;
 
     static void active( context * active) noexcept;
@@ -181,7 +184,7 @@ public:
         scheduler_( nullptr),
         ctx_( boost::context::execution_context::current() ),
         fss_data_(),
-        waiting_(),
+        wait_queue_(),
         except_(),
         tp_( (std::chrono::steady_clock::time_point::max)() ),
         properties_( nullptr) {
@@ -225,7 +228,7 @@ public:
                 BOOST_ASSERT_MSG( false, "fiber already terminated");
               }),
         fss_data_(),
-        waiting_(),
+        wait_queue_(),
         except_(),
         tp_( (std::chrono::steady_clock::time_point::max)() ),
         properties_( nullptr) {
@@ -401,16 +404,24 @@ public:
 
     std::chrono::steady_clock::duration do_wait_interval() noexcept;
 
-    bool state_is_linked() {
-        return detail::state_hook::is_linked();
+    bool runnable_is_linked() {
+        return runnable_hook_.is_linked();
     }
 
-    bool yield_is_linked() {
-        return detail::yield_hook::is_linked();
+    bool ready_is_linked() {
+        return ready_hook_.is_linked();
+    }
+
+    bool sleep_is_linked() {
+        return sleep_hook_.is_linked();
     }
 
     bool wait_is_linked() {
-        return detail::wait_hook::is_linked();
+        return wait_hook_.is_linked();
+    }
+
+    void wait_unlink() {
+        wait_hook_.unlink();
     }
 
     friend void intrusive_ptr_add_ref( context * f) {
diff --git a/include/boost/fiber/detail/queues.hpp b/include/boost/fiber/detail/queues.hpp
index 9cf679c6..e470087f 100644
--- a/include/boost/fiber/detail/queues.hpp
+++ b/include/boost/fiber/detail/queues.hpp
@@ -20,50 +20,57 @@ namespace boost {
 namespace fibers {
 namespace detail {
 
-struct state_tag;
-typedef intrusive::list_base_hook<
-    intrusive::tag< state_tag >,
+struct runnable_tag;
+typedef intrusive::list_member_hook<
+    intrusive::tag< runnable_tag >,
     intrusive::link_mode<
         intrusive::safe_link
     >
->                                       state_hook;
+>                                       runnable_hook;
 template< typename T >
-using state_queue = intrusive::list<
+using runnable_queue = intrusive::list<
                         T,
-                        intrusive::base_hook< state_hook > >;
+                        intrusive::member_hook< T, runnable_hook, & T::runnable_hook_ > >;
 
-struct yield_tag;
-typedef intrusive::list_base_hook<
-    intrusive::tag< yield_tag >,
+struct ready_tag;
+typedef intrusive::list_member_hook<
+    intrusive::tag< ready_tag >,
     intrusive::link_mode<
         intrusive::safe_link
     >
->                                       yield_hook;
+>                                       ready_hook;
 template< typename T >
-using yield_queue = intrusive::list<
+using ready_queue = intrusive::list<
                         T,
-                        intrusive::base_hook< yield_hook >,
+                        intrusive::member_hook< T, ready_hook, & T::ready_hook_ >,
+                        intrusive::constant_time_size< false > >;
+
+struct sleep_tag;
+typedef intrusive::list_member_hook<
+    intrusive::tag< sleep_tag >,
+    intrusive::link_mode<
+        intrusive::safe_link
+    >
+>                                       sleep_hook;
+template< typename T >
+using sleep_queue = intrusive::list<
+                        T,
+                        intrusive::member_hook< T, sleep_hook, & T::sleep_hook_ >,
                         intrusive::constant_time_size< false > >;
 
 struct wait_tag;
-typedef intrusive::list_base_hook<
+typedef intrusive::list_member_hook<
     intrusive::tag< wait_tag >,
     intrusive::link_mode<
-        intrusive::safe_link
+        intrusive::auto_unlink
     >
 >                                       wait_hook;
 template< typename T >
 using wait_queue = intrusive::list<
                         T,
-                        intrusive::base_hook< wait_hook >,
+                        intrusive::member_hook< T, wait_hook, & T::wait_hook_ >,
                         intrusive::constant_time_size< false > >;
 
-template< typename Lst, typename Ctx >
-void erase_and_dispose( Lst & lst, Ctx * ctx){
-    typename Lst::iterator i( Lst::s_iterator_to( * ctx) );
-    lst.erase_and_dispose( i, []( Ctx * ctx){ intrusive_ptr_release( ctx); });
-}
-
 }}}
 
 #ifdef BOOST_HAS_ABI_HEADERS
diff --git a/include/boost/fiber/mutex.hpp b/include/boost/fiber/mutex.hpp
index dba3353f..95d8e17a 100644
--- a/include/boost/fiber/mutex.hpp
+++ b/include/boost/fiber/mutex.hpp
@@ -28,12 +28,12 @@ private:
         unlocked
     };
 
-    typedef detail::wait_queue< context >   wqueue_t;
+    typedef detail::wait_queue< context >   wait_queue_t;
 
     detail::spinlock    splk_;
     mutex_status        state_;
     context::id         owner_;
-    wqueue_t            waiting_;
+    wait_queue_t            wait_queue_;
 
     bool lock_if_unlocked_();
 
diff --git a/include/boost/fiber/recursive_mutex.hpp b/include/boost/fiber/recursive_mutex.hpp
index c0ea0625..39228b96 100644
--- a/include/boost/fiber/recursive_mutex.hpp
+++ b/include/boost/fiber/recursive_mutex.hpp
@@ -32,13 +32,13 @@ private:
         unlocked
     };
 
-    typedef detail::wait_queue< context >   wqueue_t;
+    typedef detail::wait_queue< context >   wait_queue_t;
 
     detail::spinlock    splk_;
     mutex_status        state_;
     context::id         owner_;
     std::size_t         count_;
-    wqueue_t            waiting_;
+    wait_queue_t            wait_queue_;
 
     bool lock_if_unlocked_();
 
diff --git a/include/boost/fiber/recursive_timed_mutex.hpp b/include/boost/fiber/recursive_timed_mutex.hpp
index b978559b..96f01891 100644
--- a/include/boost/fiber/recursive_timed_mutex.hpp
+++ b/include/boost/fiber/recursive_timed_mutex.hpp
@@ -34,13 +34,13 @@ private:
         unlocked
     };
 
-    typedef detail::wait_queue< context >   wqueue_t;
+    typedef detail::wait_queue< context >   wait_queue_t;
 
     detail::spinlock    splk_;
     mutex_status        state_;
     context::id         owner_;
     std::size_t         count_;
-    wqueue_t            waiting_;
+    wait_queue_t            wait_queue_;
 
     bool lock_if_unlocked_();
 
diff --git a/include/boost/fiber/round_robin.hpp b/include/boost/fiber/round_robin.hpp
index a2bf56ad..672f09b1 100644
--- a/include/boost/fiber/round_robin.hpp
+++ b/include/boost/fiber/round_robin.hpp
@@ -26,9 +26,9 @@ class context;
 
 class BOOST_FIBERS_DECL round_robin : public sched_algorithm {
 private:
-    typedef detail::state_queue< context >   rqueue_t;
+    typedef detail::runnable_queue< context >   runnable_queue_t;
 
-    rqueue_t                    rqueue_;
+    runnable_queue_t        runnable_queue_;
 
 public:
     virtual void awakened( context *);
diff --git a/include/boost/fiber/scheduler.hpp b/include/boost/fiber/scheduler.hpp
index 1a9d767d..e2c125ed 100644
--- a/include/boost/fiber/scheduler.hpp
+++ b/include/boost/fiber/scheduler.hpp
@@ -9,7 +9,7 @@
 #include <cstddef>
 #include <chrono>
 #include <memory>
-#include <mutex>
+#include <vector>
 
 #include <boost/assert.hpp>
 #include <boost/config.hpp>
@@ -32,15 +32,15 @@ struct sched_algorithm;
 
 class BOOST_FIBERS_DECL scheduler {
 private:
-    typedef detail::state_queue< context >  tqueue_t;
-    typedef detail::state_queue< context >  wqueue_t;
-    typedef detail::yield_queue< context >  yqueue_t;
+    typedef detail::ready_queue< context >  ready_queue_t;
+    typedef detail::sleep_queue< context >  sleep_queue_t;
+    typedef std::vector< context * >        terminated_queue_t;
 
     std::unique_ptr< sched_algorithm >      sched_algo_;
     context                             *   main_context_;
-    wqueue_t                                wqueue_;
-    tqueue_t                                tqueue_;
-    yqueue_t                                yqueue_;
+    ready_queue_t                           ready_queue_;
+    sleep_queue_t                           sleep_queue_;
+    terminated_queue_t                      terminated_queue_;
     std::chrono::steady_clock::duration     wait_interval_;
 
     void resume_( context *, context *);
@@ -67,7 +67,7 @@ public:
 
     void join( context *,context *);
 
-    std::size_t ready_fibers() const noexcept;
+    size_t ready_fibers() const noexcept;
 
     void set_sched_algo( std::unique_ptr< sched_algorithm >);
 
diff --git a/include/boost/fiber/timed_mutex.hpp b/include/boost/fiber/timed_mutex.hpp
index 318ba260..026fcacd 100644
--- a/include/boost/fiber/timed_mutex.hpp
+++ b/include/boost/fiber/timed_mutex.hpp
@@ -31,12 +31,12 @@ private:
         unlocked
     };
 
-    typedef detail::wait_queue< context >   wqueue_t;
+    typedef detail::wait_queue< context >   wait_queue_t;
 
     detail::spinlock    splk_;
     mutex_status        state_;
     context::id         owner_;
-    wqueue_t            waiting_;
+    wait_queue_t            wait_queue_;
 
     bool lock_if_unlocked_();
 
diff --git a/src/condition.cpp b/src/condition.cpp
index 94208af8..3e9cd8ff 100644
--- a/src/condition.cpp
+++ b/src/condition.cpp
@@ -17,11 +17,11 @@ namespace fibers {
 
 condition::condition() :
     splk_(),
-    waiting_() {
+    wait_queue_() {
 }
 
 condition::~condition() {
-    BOOST_ASSERT( waiting_.empty() );
+    BOOST_ASSERT( wait_queue_.empty() );
 }
 
 void
@@ -30,9 +30,9 @@ condition::notify_one() {
 
     detail::spinlock_lock lk( splk_);
     // get one waiting fiber
-    if ( ! waiting_.empty() ) {
-        f = & waiting_.front();
-        waiting_.pop_front();
+    if ( ! wait_queue_.empty() ) {
+        f = & wait_queue_.front();
+        wait_queue_.pop_front();
     }
     lk.unlock();
 
@@ -44,11 +44,11 @@ condition::notify_one() {
 
 void
 condition::notify_all() {
-    wqueue_t waiting;
+    wait_queue_t waiting;
 
     detail::spinlock_lock lk( splk_);
     // get all waiting fibers
-    waiting.swap( waiting_);
+    waiting.swap( wait_queue_);
     lk.unlock();
 
     // notify all waiting fibers
diff --git a/src/context.cpp b/src/context.cpp
index a3be082f..7add37c3 100644
--- a/src/context.cpp
+++ b/src/context.cpp
@@ -41,7 +41,7 @@ context::active( context * active) noexcept {
 }
 
 context::~context() {
-    BOOST_ASSERT( waiting_.empty() );
+    BOOST_ASSERT( wait_queue_.empty() );
     delete properties_;
 }
 
@@ -53,7 +53,7 @@ context::release() {
 
     // get all waiting fibers
     splk_.lock();
-    waiting.swap( waiting_);
+    waiting.swap( wait_queue_);
     splk_.unlock();
 
     // notify all waiting fibers
@@ -78,7 +78,7 @@ context::join( context * f) {
     if ( is_terminated() ) {
         return false;
     }
-    waiting_.push_back( f);
+    wait_queue_.push_back( f);
     return true;
 }
 
diff --git a/src/mutex.cpp b/src/mutex.cpp
index 5d2f1438..08f14eb0 100644
--- a/src/mutex.cpp
+++ b/src/mutex.cpp
@@ -37,12 +37,12 @@ mutex::mutex() :
     splk_(),
 	state_( mutex_status::unlocked),
     owner_(),
-    waiting_() {
+    wait_queue_() {
 }
 
 mutex::~mutex() {
     BOOST_ASSERT( ! owner_);
-    BOOST_ASSERT( waiting_.empty() );
+    BOOST_ASSERT( wait_queue_.empty() );
 }
 
 void
@@ -58,7 +58,7 @@ mutex::lock() {
 
         // store this fiber in order to be notified later
         BOOST_ASSERT( ! f->wait_is_linked() );
-        waiting_.push_back( * f);
+        wait_queue_.push_back( * f);
 
         // suspend this fiber
         context::active()->do_wait( lk);
@@ -87,9 +87,9 @@ mutex::unlock() {
 
     detail::spinlock_lock lk( splk_);
     context * f( nullptr);
-    if ( ! waiting_.empty() ) {
-        f = & waiting_.front();
-        waiting_.pop_front();
+    if ( ! wait_queue_.empty() ) {
+        f = & wait_queue_.front();
+        wait_queue_.pop_front();
         BOOST_ASSERT( nullptr != f);
     }
     owner_ = context::id();
diff --git a/src/recursive_mutex.cpp b/src/recursive_mutex.cpp
index f739a077..bb43f385 100644
--- a/src/recursive_mutex.cpp
+++ b/src/recursive_mutex.cpp
@@ -42,13 +42,13 @@ recursive_mutex::recursive_mutex() :
 	state_( mutex_status::unlocked),
     owner_(),
     count_( 0),
-    waiting_() {
+    wait_queue_() {
 }
 
 recursive_mutex::~recursive_mutex() {
     BOOST_ASSERT( ! owner_);
     BOOST_ASSERT( 0 == count_);
-    BOOST_ASSERT( waiting_.empty() );
+    BOOST_ASSERT( wait_queue_.empty() );
 }
 
 void
@@ -64,7 +64,7 @@ recursive_mutex::lock() {
 
         // store this fiber in order to be notified later
         BOOST_ASSERT( ! f->wait_is_linked() );
-        waiting_.push_back( * f);
+        wait_queue_.push_back( * f);
 
         // suspend this fiber
         context::active()->do_wait( lk);
@@ -94,9 +94,9 @@ recursive_mutex::unlock() {
     detail::spinlock_lock lk( splk_);
     context * f( nullptr);
     if ( 0 == --count_) {
-        if ( ! waiting_.empty() ) {
-            f = & waiting_.front();
-            waiting_.pop_front();
+        if ( ! wait_queue_.empty() ) {
+            f = & wait_queue_.front();
+            wait_queue_.pop_front();
             BOOST_ASSERT( nullptr != f);
         }
         owner_ = context::id();
diff --git a/src/recursive_timed_mutex.cpp b/src/recursive_timed_mutex.cpp
index e45d9740..f805f627 100644
--- a/src/recursive_timed_mutex.cpp
+++ b/src/recursive_timed_mutex.cpp
@@ -42,13 +42,13 @@ recursive_timed_mutex::recursive_timed_mutex() :
 	state_( mutex_status::unlocked),
     owner_(),
     count_( 0),
-    waiting_() {
+    wait_queue_() {
 }
 
 recursive_timed_mutex::~recursive_timed_mutex() {
     BOOST_ASSERT( ! owner_);
     BOOST_ASSERT( 0 == count_);
-    BOOST_ASSERT( waiting_.empty() );
+    BOOST_ASSERT( wait_queue_.empty() );
 }
 
 void
@@ -64,7 +64,7 @@ recursive_timed_mutex::lock() {
 
         // store this fiber in order to be notified later
         BOOST_ASSERT( ! f->wait_is_linked() );
-        waiting_.push_back( * f);
+        wait_queue_.push_back( * f);
 
         // suspend this fiber
         context::active()->do_wait( lk);
@@ -103,12 +103,12 @@ recursive_timed_mutex::try_lock_until_( std::chrono::steady_clock::time_point co
 
         // store this fiber in order to be notified later
         BOOST_ASSERT( ! f->wait_is_linked() );
-        waiting_.push_back( * f);
+        wait_queue_.push_back( * f);
 
         // suspend this fiber until notified or timed-out
         if ( ! context::active()->do_wait_until( timeout_time, lk) ) {
             lk.lock();
-            detail::erase_and_dispose( waiting_, f);
+            f->wait_unlink();
             lk.unlock();
             return false;
         }
@@ -123,9 +123,9 @@ recursive_timed_mutex::unlock() {
     detail::spinlock_lock lk( splk_);
     context * f( nullptr);
     if ( 0 == --count_) {
-        if ( ! waiting_.empty() ) {
-            f = & waiting_.front();
-            waiting_.pop_front();
+        if ( ! wait_queue_.empty() ) {
+            f = & wait_queue_.front();
+            wait_queue_.pop_front();
             BOOST_ASSERT( nullptr != f);
         }
         owner_ = context::id();
diff --git a/src/round_robin.cpp b/src/round_robin.cpp
index 124e55de..f12ab429 100644
--- a/src/round_robin.cpp
+++ b/src/round_robin.cpp
@@ -19,16 +19,16 @@ void
 round_robin::awakened( context * f) {
     BOOST_ASSERT( nullptr != f);
 
-    BOOST_ASSERT( ! f->state_is_linked() );
-    rqueue_.push_back( * f);
+    BOOST_ASSERT( ! f->runnable_is_linked() );
+    runnable_queue_.push_back( * f);
 }
 
 context *
 round_robin::pick_next() {
     context * victim( nullptr);
-    if ( ! rqueue_.empty() ) {
-        victim = & rqueue_.front();
-        rqueue_.pop_front();
+    if ( ! runnable_queue_.empty() ) {
+        victim = & runnable_queue_.front();
+        runnable_queue_.pop_front();
         BOOST_ASSERT( nullptr != victim);
     }
     return victim;
@@ -36,7 +36,7 @@ round_robin::pick_next() {
 
 std::size_t
 round_robin::ready_fibers() const noexcept {
-    return rqueue_.size();
+    return runnable_queue_.size();
 }
 
 }}
diff --git a/src/scheduler.cpp b/src/scheduler.cpp
index 7c9cda26..da2579db 100644
--- a/src/scheduler.cpp
+++ b/src/scheduler.cpp
@@ -27,9 +27,9 @@ namespace fibers {
 scheduler::scheduler( context * main_context) noexcept :
     sched_algo_( new round_robin() ),
     main_context_( main_context),
-    wqueue_(),
-    tqueue_(),
-    yqueue_(),
+    ready_queue_(),
+    sleep_queue_(),
+    terminated_queue_(),
     wait_interval_( std::chrono::milliseconds( 10) ) {
 }
 
@@ -39,15 +39,15 @@ scheduler::~scheduler() noexcept {
         // NOTE: at this stage the fibers in the waiting-queue
         //       can only be detached fibers
         //       interrupt all waiting fibers (except main-fiber)
-        for ( context & f : wqueue_) {
+        for ( context & f : sleep_queue_) {
             f.request_interruption( true);
         }
         // move all fibers which are ready (state_ready)
         // from waiting-queue to the runnable-queue
         std::chrono::steady_clock::time_point now(
                 std::chrono::steady_clock::now() );
-        wqueue_t::iterator e = wqueue_.end();
-        for ( wqueue_t::iterator i = wqueue_.begin(); i != e;) {
+        sleep_queue_t::iterator e = sleep_queue_.end();
+        for ( sleep_queue_t::iterator i = sleep_queue_.begin(); i != e;) {
             context * f = & ( * i);
             BOOST_ASSERT( ! f->is_running() );
             BOOST_ASSERT( ! f->is_terminated() );
@@ -59,12 +59,14 @@ scheduler::~scheduler() noexcept {
             }
 
             if ( f->is_ready() ) {
-                i = wqueue_.erase( i);
-                // Pass the newly-unlinked context* to sched_algo.
+                i = sleep_queue_.erase( i);
+                // unlink after accesing iterator
                 f->time_point_reset();
-                BOOST_ASSERT( ! f->state_is_linked() );
-                BOOST_ASSERT( ! f->wait_is_linked() );
-                BOOST_ASSERT( ! f->yield_is_linked() );
+                // Pass the newly-unlinked context* to sched_algo.
+                BOOST_ASSERT( ! f->runnable_is_linked() );
+                BOOST_ASSERT( ! f->ready_is_linked() );
+                BOOST_ASSERT( ! f->sleep_is_linked() );
+                //BOOST_ASSERT( ! f->wait_is_linked() );
                 sched_algo_->awakened( f);
             } else {
                 ++i;
@@ -72,10 +74,11 @@ scheduler::~scheduler() noexcept {
         }
         // pop new fiber from ready-queue
         context * f( sched_algo_->pick_next() );
-        BOOST_ASSERT( ! f->state_is_linked() );
-        BOOST_ASSERT( ! f->wait_is_linked() );
-        BOOST_ASSERT( ! f->yield_is_linked() );
         if ( nullptr != f) {
+            BOOST_ASSERT( ! f->runnable_is_linked() );
+            BOOST_ASSERT( ! f->ready_is_linked() );
+            BOOST_ASSERT( ! f->sleep_is_linked() );
+            //BOOST_ASSERT( ! f->wait_is_linked() );
             BOOST_ASSERT_MSG( f->is_ready(), "fiber with invalid state in ready-queue");
             // set scheduler
             f->set_scheduler( this);
@@ -86,29 +89,29 @@ scheduler::~scheduler() noexcept {
             // set main-fiber to state_waiting
             main_context_->set_waiting();
             // push main-fiber to waiting-queue
-            BOOST_ASSERT( ! main_context_->state_is_linked() );
-            yqueue_.push_back( * main_context_);
+            BOOST_ASSERT( ! main_context_->runnable_is_linked() );
+            ready_queue_.push_back( * main_context_);
             // resume fiber f
             resume_( main_context_, f);
-        } else if ( wqueue_.empty() ) {
+        } else if ( sleep_queue_.empty() ) {
             // ready- and waiting-queue are empty so we can quit
             break;
         }
     }
     // destroy terminated fibers from terminated-queue
-    tqueue_t::iterator e = tqueue_.end();
-    for ( tqueue_t::iterator i = tqueue_.begin(); i != e;) {
-        context * f( & ( * i) );
+    for ( context * f : terminated_queue_) {
         BOOST_ASSERT( f->is_terminated() );
-        i = tqueue_.erase( i);
-        BOOST_ASSERT( ! f->state_is_linked() );
+        BOOST_ASSERT( ! f->runnable_is_linked() );
+        BOOST_ASSERT( ! f->ready_is_linked() );
+        BOOST_ASSERT( ! f->sleep_is_linked() );
         BOOST_ASSERT( ! f->wait_is_linked() );
-        BOOST_ASSERT( ! f->yield_is_linked() );
         intrusive_ptr_release( f); // might call ~context()
     }
+    terminated_queue_.clear();
     BOOST_ASSERT( context::active() == main_context_);
-    BOOST_ASSERT( wqueue_.empty() );
-    BOOST_ASSERT( yqueue_.empty() );
+    BOOST_ASSERT( ready_queue_.empty() );
+    BOOST_ASSERT( sleep_queue_.empty() );
+    BOOST_ASSERT( terminated_queue_.empty() );
     BOOST_ASSERT( 0 == sched_algo_->ready_fibers() );
 }
 
@@ -132,8 +135,8 @@ scheduler::resume_( context * af, context * f) {
     context::active( f);
     // push terminated fibers to terminated-queue
     if ( af->is_terminated() ) {
-        BOOST_ASSERT( ! af->state_is_linked() );
-        tqueue_.push_back( * af);
+        BOOST_ASSERT( ! af->runnable_is_linked() );
+        terminated_queue_.push_back( af);
     }
     // resume active-fiber == f
     f->resume();
@@ -145,9 +148,9 @@ scheduler::spawn( context * f) {
     BOOST_ASSERT( f->is_ready() );
     BOOST_ASSERT( f != context::active() );
     // add new fiber to the scheduler
-    BOOST_ASSERT( ! f->state_is_linked() );
-    BOOST_ASSERT( ! f->wait_is_linked() );
-    BOOST_ASSERT( ! f->yield_is_linked() );
+    BOOST_ASSERT( ! f->runnable_is_linked() );
+    BOOST_ASSERT( ! f->ready_is_linked() );
+    BOOST_ASSERT( ! f->sleep_is_linked() );
     sched_algo_->awakened( f);
 }
 
@@ -158,15 +161,16 @@ scheduler::run( context * af) {
     for (;;) {
         {
             // move all fibers in yield-queue to ready-queue
-            yqueue_t::iterator e = yqueue_.end();
-            for ( yqueue_t::iterator i = yqueue_.begin(); i != e;) {
+            ready_queue_t::iterator e = ready_queue_.end();
+            for ( ready_queue_t::iterator i = ready_queue_.begin(); i != e;) {
                 context * f = & ( * i);
                 BOOST_ASSERT( f->is_ready() );
 
-                i = yqueue_.erase( i);
-                BOOST_ASSERT( ! f->state_is_linked() );
-                BOOST_ASSERT( ! f->wait_is_linked() );
-                BOOST_ASSERT( ! f->yield_is_linked() );
+                i = ready_queue_.erase( i);
+                BOOST_ASSERT( ! f->runnable_is_linked() );
+                BOOST_ASSERT( ! f->ready_is_linked() );
+                BOOST_ASSERT( ! f->sleep_is_linked() );
+                //BOOST_ASSERT( ! f->wait_is_linked() );
                 sched_algo_->awakened( f);
             }
         }
@@ -175,8 +179,8 @@ scheduler::run( context * af) {
             // from waiting-queue to the ready-queue
             std::chrono::steady_clock::time_point now(
                     std::chrono::steady_clock::now() );
-            wqueue_t::iterator e = wqueue_.end();
-            for ( wqueue_t::iterator i = wqueue_.begin(); i != e;) {
+            sleep_queue_t::iterator e = sleep_queue_.end();
+            for ( sleep_queue_t::iterator i = sleep_queue_.begin(); i != e;) {
                 context * f = & ( * i);
                 BOOST_ASSERT( ! f->is_running() );
                 BOOST_ASSERT( ! f->is_terminated() );
@@ -186,12 +190,14 @@ scheduler::run( context * af) {
                     f->set_ready();
                 }
                 if ( f->is_ready() ) {
-                    i = wqueue_.erase( i);
-                    // Pass the newly-unlinked context* to sched_algo.
+                    i = sleep_queue_.erase( i);
+                    // unlink only after accessing iterator
                     f->time_point_reset();
-                    BOOST_ASSERT( ! f->state_is_linked() );
-                    BOOST_ASSERT( ! f->wait_is_linked() );
-                    BOOST_ASSERT( ! f->yield_is_linked() );
+                    // Pass the newly-unlinked context* to sched_algo.
+                    BOOST_ASSERT( ! f->runnable_is_linked() );
+                    BOOST_ASSERT( ! f->ready_is_linked() );
+                    BOOST_ASSERT( ! f->sleep_is_linked() );
+                    //BOOST_ASSERT( ! f->wait_is_linked() );
                     sched_algo_->awakened( f);
                 } else {
                     ++i;
@@ -201,20 +207,23 @@ scheduler::run( context * af) {
         // pop new fiber from ready-queue
         context * f( sched_algo_->pick_next() );
         if ( nullptr != f) {
+            BOOST_ASSERT( ! f->runnable_is_linked() );
+            BOOST_ASSERT( ! f->ready_is_linked() );
+            BOOST_ASSERT( ! f->sleep_is_linked() );
+            //BOOST_ASSERT( ! f->wait_is_linked() );
             BOOST_ASSERT_MSG( f->is_ready(), "fiber with invalid state in ready-queue");
             // resume fiber f
             resume_( af, f);
             // destroy terminated fibers from terminated-queue
-            tqueue_t::iterator e = tqueue_.end();
-            for ( tqueue_t::iterator i = tqueue_.begin(); i != e;) {
-                context * f( & ( * i) );
+            for ( context * f : terminated_queue_) {
                 BOOST_ASSERT( f->is_terminated() );
-                i = tqueue_.erase( i);
-                BOOST_ASSERT( ! f->state_is_linked() );
+                BOOST_ASSERT( ! f->runnable_is_linked() );
+                BOOST_ASSERT( ! f->ready_is_linked() );
+                BOOST_ASSERT( ! f->sleep_is_linked() );
                 BOOST_ASSERT( ! f->wait_is_linked() );
-                BOOST_ASSERT( ! f->yield_is_linked() );
                 intrusive_ptr_release( f); // might call ~context()
             }
+            terminated_queue_.clear();
             return;
         } else {
             // no fibers ready to run; the thread should sleep
@@ -246,8 +255,8 @@ scheduler::wait_until( context * af,
     lk.unlock();
     // push active-fiber to waiting-queue
     af->time_point( timeout_time);
-    BOOST_ASSERT( ! af->state_is_linked() );
-    wqueue_.push_back( * af);
+    BOOST_ASSERT( ! af->sleep_is_linked() );
+    sleep_queue_.push_back( * af);
     // switch to another fiber
     run( af);
     // fiber has been resumed
@@ -264,9 +273,9 @@ scheduler::yield( context * af) {
     BOOST_ASSERT( af->is_running() );
     // set active-fiber to state_waiting
     af->set_ready();
-    // push active-fiber to yqueue_
-    BOOST_ASSERT( ! af->yield_is_linked() );
-    yqueue_.push_back( * af);
+    // push active-fiber to ready_queue_
+    BOOST_ASSERT( ! af->ready_is_linked() );
+    ready_queue_.push_back( * af);
     // switch to another fiber
     run( af);
     // fiber has been resumed
@@ -284,8 +293,8 @@ scheduler::join( context * af, context * f) {
     // set active-fiber to state_waiting
     af->set_waiting();
     // push active-fiber to waiting-queue
-    BOOST_ASSERT( ! af->state_is_linked() );
-    wqueue_.push_back( * af);
+    BOOST_ASSERT( ! af->sleep_is_linked() );
+    sleep_queue_.push_back( * af);
     // add active-fiber to joinig-list of f
     if ( ! f->join( af) ) {
         // f must be already terminated therefore we set
diff --git a/src/timed_mutex.cpp b/src/timed_mutex.cpp
index 48ce5b9a..475ed2b2 100644
--- a/src/timed_mutex.cpp
+++ b/src/timed_mutex.cpp
@@ -37,12 +37,12 @@ timed_mutex::timed_mutex() :
     splk_(),
 	state_( mutex_status::unlocked),
     owner_(),
-    waiting_() {
+    wait_queue_() {
 }
 
 timed_mutex::~timed_mutex() {
     BOOST_ASSERT( ! owner_);
-    BOOST_ASSERT( waiting_.empty() );
+    BOOST_ASSERT( wait_queue_.empty() );
 }
 
 void
@@ -58,7 +58,7 @@ timed_mutex::lock() {
 
         // store this fiber in order to be notified later
         BOOST_ASSERT( ! f->wait_is_linked() );
-        waiting_.push_back( * f);
+        wait_queue_.push_back( * f);
 
         // suspend this fiber
         context::active()->do_wait( lk);
@@ -97,12 +97,12 @@ timed_mutex::try_lock_until_( std::chrono::steady_clock::time_point const& timeo
 
         // store this fiber in order to be notified later
         BOOST_ASSERT( ! f->wait_is_linked() );
-        waiting_.push_back( * f);
+        wait_queue_.push_back( * f);
 
         // suspend this fiber until notified or timed-out
         if ( ! context::active()->do_wait_until( timeout_time, lk) ) {
             lk.lock();
-            detail::erase_and_dispose( waiting_, f);
+            f->wait_unlink();
             lk.unlock();
             return false;
         }
@@ -116,9 +116,9 @@ timed_mutex::unlock() {
 
     detail::spinlock_lock lk( splk_);
     context * f( nullptr);
-    if ( ! waiting_.empty() ) {
-        f = & waiting_.front();
-        waiting_.pop_front();
+    if ( ! wait_queue_.empty() ) {
+        f = & wait_queue_.front();
+        wait_queue_.pop_front();
         BOOST_ASSERT( nullptr != f);
     }
     owner_ = context::id();