diff --git a/srsenb/hdr/stack/mac/nr/sched_nr_common.h b/srsenb/hdr/stack/mac/nr/sched_nr_common.h
index 75d7ad1aa..701fb1d31 100644
--- a/srsenb/hdr/stack/mac/nr/sched_nr_common.h
+++ b/srsenb/hdr/stack/mac/nr/sched_nr_common.h
@@ -44,6 +44,46 @@ struct sched_params {
 
 using rbgmask_t = srsran::bounded_bitset<SCHED_NR_MAX_NOF_RBGS, true>;
 
+struct resource_guard {
+public:
+  resource_guard()                            = default;
+  resource_guard(const resource_guard& other) = delete;
+  resource_guard(resource_guard&& other)      = delete;
+  resource_guard& operator=(const resource_guard& other) = delete;
+  resource_guard& operator=(resource_guard&& other) = delete;
+  bool            busy() const { return flag; }
+
+  struct token {
+    token() = default;
+    token(resource_guard& parent) : flag(parent.busy() ? nullptr : &parent.flag)
+    {
+      if (flag != nullptr) {
+        *flag = true;
+      }
+    }
+    token(token&&) noexcept = default;
+    token& operator=(token&&) noexcept = default;
+    void   release() { flag.reset(); }
+    bool   owns_token() const { return flag != nullptr; }
+    bool   empty() const { return flag == nullptr; }
+
+  private:
+    struct release_deleter {
+      void operator()(bool* ptr)
+      {
+        if (ptr != nullptr) {
+          srsran_assert(*ptr == true, "resource token: detected inconsistency token state");
+          *ptr = false;
+        }
+      }
+    };
+    std::unique_ptr<bool, release_deleter> flag;
+  };
+
+private:
+  bool flag = false;
+};
+
 } // namespace sched_nr_impl
 
 } // namespace srsenb
diff --git a/srsenb/hdr/stack/mac/nr/sched_nr_ue.h b/srsenb/hdr/stack/mac/nr/sched_nr_ue.h
index 16688f11c..327d89d3e 100644
--- a/srsenb/hdr/stack/mac/nr/sched_nr_ue.h
+++ b/srsenb/hdr/stack/mac/nr/sched_nr_ue.h
@@ -30,11 +30,11 @@ class slot_ue
 {
 public:
   slot_ue() = default;
-  explicit slot_ue(bool& busy_signal, tti_point tti_rx_, uint32_t cc);
+  explicit slot_ue(resource_guard::token ue_token, tti_point tti_rx_, uint32_t cc);
   ~slot_ue();
   slot_ue(slot_ue&&) noexcept = default;
   slot_ue& operator=(slot_ue&&) noexcept = default;
-  bool     empty() const { return busy_signal == nullptr; }
+  bool     empty() const { return ue_token.empty(); }
   void     release();
 
   tti_point tti_rx;
@@ -51,10 +51,7 @@ public:
   harq_proc* h_ul = nullptr;
 
 private:
-  struct noop {
-    void operator()(bool* ptr) {}
-  };
-  std::unique_ptr<bool, noop> busy_signal;
+  resource_guard::token ue_token;
 };
 
 class ue_carrier
@@ -77,8 +74,8 @@ public:
 private:
   const sched_nr_ue_cfg* cfg = nullptr;
 
-  bool      busy{false};
-  tti_point last_tti_rx;
+  resource_guard busy;
+  tti_point      last_tti_rx;
 
   srsran::deque<srsran::move_callback<void(ue_carrier&)> > pending_feedback;
 };
diff --git a/srsenb/src/stack/mac/nr/sched_nr_ue.cc b/srsenb/src/stack/mac/nr/sched_nr_ue.cc
index 9d3d0dbef..5e8d3b570 100644
--- a/srsenb/src/stack/mac/nr/sched_nr_ue.cc
+++ b/srsenb/src/stack/mac/nr/sched_nr_ue.cc
@@ -15,8 +15,8 @@
 namespace srsenb {
 namespace sched_nr_impl {
 
-slot_ue::slot_ue(bool& busy_signal_, tti_point tti_rx_, uint32_t cc_) :
-  busy_signal(&busy_signal_), tti_rx(tti_rx_), cc(cc_)
+slot_ue::slot_ue(resource_guard::token ue_token_, tti_point tti_rx_, uint32_t cc_) :
+  ue_token(std::move(ue_token_)), tti_rx(tti_rx_), cc(cc_)
 {}
 
 slot_ue::~slot_ue()
@@ -26,9 +26,7 @@ slot_ue::~slot_ue()
 
 void slot_ue::release()
 {
-  if (busy_signal != nullptr) {
-    *busy_signal = false;
-  }
+  ue_token.release();
 }
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -48,12 +46,11 @@ void ue_carrier::push_feedback(srsran::move_callback<void(ue_carrier&)> callback
 
 slot_ue ue_carrier::try_reserve(tti_point tti_rx, const sched_nr_ue_cfg& uecfg_)
 {
-  slot_ue sfu = (busy) ? slot_ue() : slot_ue(busy, tti_rx, cc);
+  slot_ue sfu(busy, tti_rx, cc);
   if (sfu.empty()) {
     return sfu;
   }
   // successfully acquired. Process any CC-specific pending feedback
-  busy = true;
   if (cfg != &uecfg_) {
     set_cfg(uecfg_);
   }
diff --git a/srsenb/src/stack/mac/nr/sched_nr_worker.cc b/srsenb/src/stack/mac/nr/sched_nr_worker.cc
index ad8089844..50ed4d71f 100644
--- a/srsenb/src/stack/mac/nr/sched_nr_worker.cc
+++ b/srsenb/src/stack/mac/nr/sched_nr_worker.cc
@@ -111,8 +111,13 @@ sched_worker_manager::sched_worker_manager(ue_map_t& ue_db_, const sched_params&
 
 sched_worker_manager::~sched_worker_manager()
 {
-  for (uint32_t sf = 0; sf < slot_ctxts.size(); ++sf) {
-    sem_destroy(&slot_ctxts[sf]->sf_sem);
+  // acquire all slot worker contexts
+  for (auto& slot_ctxt : slot_ctxts) {
+    sem_wait(&slot_ctxt->sf_sem);
+  }
+  // destroy all slot worker contexts
+  for (auto& slot_ctxt : slot_ctxts) {
+    sem_destroy(&slot_ctxt->sf_sem);
   }
 }
 
diff --git a/srsenb/test/mac/nr/sched_nr_test.cc b/srsenb/test/mac/nr/sched_nr_test.cc
index d60a3b265..75c2d7522 100644
--- a/srsenb/test/mac/nr/sched_nr_test.cc
+++ b/srsenb/test/mac/nr/sched_nr_test.cc
@@ -20,6 +20,7 @@ struct task_job_manager {
   std::mutex              mutex;
   std::condition_variable cond_var;
   int                     tasks       = 0;
+  int                     res_count   = 0;
   int                     pdsch_count = 0;
   int                     max_tasks   = std::numeric_limits<int>::max() / 2;
 
@@ -35,6 +36,7 @@ struct task_job_manager {
   {
     std::unique_lock<std::mutex> lock(mutex);
     TESTASSERT(res.dl_res.data.size() <= 1);
+    res_count++;
     pdsch_count += res.dl_res.data.size();
     if (tasks-- >= max_tasks or tasks == 0) {
       cond_var.notify_one();
@@ -47,6 +49,7 @@ struct task_job_manager {
       cond_var.wait(lock);
     }
   }
+  void print_results() const { printf("TESTER: %f PDSCH/{slot,cc} were allocated\n", pdsch_count / (double)res_count); }
 };
 
 void sched_nr_cfg_serialized_test()
@@ -66,7 +69,7 @@ void sched_nr_cfg_serialized_test()
   uecfg.carriers[0].active = true;
   sched.ue_cfg(0x46, uecfg);
 
-  for (uint32_t nof_ttis = 0; nof_ttis < 1000; ++nof_ttis) {
+  for (uint32_t nof_ttis = 0; nof_ttis < max_nof_ttis; ++nof_ttis) {
     tti_point tti(nof_ttis % 10240);
     sched.new_tti(tti);
     for (uint32_t cc = 0; cc < cells_cfg.size(); ++cc) {
@@ -77,7 +80,7 @@ void sched_nr_cfg_serialized_test()
     }
   }
 
-  printf("TESTER: %f PDSCH/slot were allocated\n", tasks.pdsch_count / (double)max_nof_ttis);
+  tasks.print_results();
 }
 
 void sched_nr_cfg_parallel_cc_test()
@@ -114,7 +117,7 @@ void sched_nr_cfg_parallel_cc_test()
 
   tasks.wait_task_finish();
 
-  printf("TESTER: %f PDSCH/slot were allocated\n", tasks.pdsch_count / (double)max_nof_ttis);
+  tasks.print_results();
 }
 
 void sched_nr_cfg_parallel_sf_test()
@@ -141,8 +144,8 @@ void sched_nr_cfg_parallel_sf_test()
   for (uint32_t nof_ttis = 0; nof_ttis < max_nof_ttis; ++nof_ttis) {
     tti_point tti(nof_ttis % 10240);
     sched.new_tti(tti);
-    tasks.start_task();
     for (uint32_t cc = 0; cc < cells_cfg.size(); ++cc) {
+      tasks.start_task();
       srsran::get_background_workers().push_task([cc, &sched, tti, &tasks]() {
         sched_nr_res_t res;
         TESTASSERT(sched.generate_sched_result(tti, cc, res) == SRSRAN_SUCCESS);
@@ -153,7 +156,7 @@ void sched_nr_cfg_parallel_sf_test()
 
   tasks.wait_task_finish();
 
-  printf("TESTER: %f PDSCH/slot were allocated\n", tasks.pdsch_count / (double)max_nof_ttis);
+  tasks.print_results();
 }
 
 } // namespace srsenb
@@ -169,5 +172,5 @@ int main()
 
   srsenb::sched_nr_cfg_serialized_test();
   srsenb::sched_nr_cfg_parallel_cc_test();
-  //  srsenb::sched_nr_cfg_parallel_sf_test();
+  srsenb::sched_nr_cfg_parallel_sf_test();
 }
\ No newline at end of file