diff --git a/util/Condition.cc b/util/Condition.cc
deleted file mode 100644
index f1fefac6..00000000
--- a/util/Condition.cc
+++ /dev/null
@@ -1,58 +0,0 @@
-// OpenSTA, Static Timing Analyzer
-// Copyright (c) 2020, Parallax Software, Inc.
-// 
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-// 
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-// 
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-#include "Machine.hh"
-#include "Condition.hh"
-#include "ThreadException.hh"
-#include "Mutex.hh"
-
-namespace sta {
-
-Condition::Condition()
-{
-  int error = pthread_cond_init(&condition_, NULL);
-  CheckThreadError(error);
-}
-
-Condition::~Condition()
-{
-  pthread_cond_destroy(&condition_);
-}
-
-void
-Condition::signal()
-{
-  int error = pthread_cond_signal(&condition_);
-  CheckThreadError(error);
-}
-
-
-void
-Condition::broadcast()
-{
-  int error = pthread_cond_broadcast(&condition_);
-  CheckThreadError(error);
-}
-
-
-void
-Condition::wait(Mutex &mutex)
-{
-  int error = pthread_cond_wait(&condition_, &mutex.mutex_);
-  CheckThreadError(error);
-}
-
-} // namespace
diff --git a/util/Condition.hh b/util/Condition.hh
deleted file mode 100644
index e0afcd86..00000000
--- a/util/Condition.hh
+++ /dev/null
@@ -1,41 +0,0 @@
-// OpenSTA, Static Timing Analyzer
-// Copyright (c) 2020, Parallax Software, Inc.
-// 
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-// 
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-// 
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-#ifndef STA_CONDITION_H
-#define STA_CONDITION_H
-
-#include "Pthread.hh"
-
-namespace sta {
-
-class Mutex;
-
-// C++ wrapper/facade for pthread_cond_t.
-class Condition
-{
-public:
-  Condition();
-  ~Condition();
-  void signal();
-  void broadcast();
-  void wait(Mutex &mutex);
-
-private:
-  pthread_cond_t condition_;
-};
-
-} // namespace
-#endif
diff --git a/util/ReadWriteLock.cc b/util/ReadWriteLock.cc
deleted file mode 100644
index b3b67335..00000000
--- a/util/ReadWriteLock.cc
+++ /dev/null
@@ -1,33 +0,0 @@
-// OpenSTA, Static Timing Analyzer
-// Copyright (c) 2020, Parallax Software, Inc.
-// 
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-// 
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-// 
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-#include "Machine.hh"
-#include "ReadWriteLock.hh"
-
-namespace sta {
-
-ReadWriteLock::ReadWriteLock()
-{
-  int error = pthread_rwlock_init(&rw_lock_, NULL);
-  CheckThreadError(error);
-}
-
-ReadWriteLock::~ReadWriteLock()
-{
-  pthread_rwlock_destroy(&rw_lock_);
-}
-
-} // namespace
diff --git a/util/ReadWriteLock.hh b/util/ReadWriteLock.hh
deleted file mode 100644
index b4b20a8a..00000000
--- a/util/ReadWriteLock.hh
+++ /dev/null
@@ -1,66 +0,0 @@
-// OpenSTA, Static Timing Analyzer
-// Copyright (c) 2020, Parallax Software, Inc.
-// 
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-// 
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-// 
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-#ifndef STA_READ_WRITE_LOCK_H
-#define STA_READ_WRITE_LOCK_H
-
-#include "DisallowCopyAssign.hh"
-#include "Error.hh"
-#include "Pthread.hh"
-#include "Mutex.hh"
-#include "Condition.hh"
-
-namespace sta {
-
-// C++ wrapper/facade for pthread_rwlock_t.
-class ReadWriteLock
-{
-public:
-  ReadWriteLock();
-  ~ReadWriteLock();
-  void readLock();
-  void writeLock();
-  void unlock();
-
-private:
-  DISALLOW_COPY_AND_ASSIGN(ReadWriteLock);
-
-  pthread_rwlock_t rw_lock_;
-};
-
-inline void
-ReadWriteLock::readLock()
-{
-  int error = pthread_rwlock_rdlock(&rw_lock_);
-  CheckThreadError(error);
-}
-
-inline void
-ReadWriteLock::writeLock()
-{
-  int error = pthread_rwlock_wrlock(&rw_lock_);
-  CheckThreadError(error);
-}
-
-inline void
-ReadWriteLock::unlock()
-{
-  int error = pthread_rwlock_unlock(&rw_lock_);
-  CheckThreadError(error);
-}
-
-} // namespace
-#endif
diff --git a/util/Thread.cc b/util/Thread.cc
deleted file mode 100644
index 8c9f405f..00000000
--- a/util/Thread.cc
+++ /dev/null
@@ -1,51 +0,0 @@
-// OpenSTA, Static Timing Analyzer
-// Copyright (c) 2020, Parallax Software, Inc.
-// 
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-// 
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-// 
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-#include "Machine.hh"
-#include "ThreadException.hh"
-#include "ThreadWorker.hh"
-#include "Thread.hh"
-
-namespace sta {
-
-ThreadPool Thread::pool_;
-
-Thread::Thread() :
-  worker_(NULL)
-{
-}
-
-void
-Thread::beginTask(ThreadFunc func,
-		  void *arg)
-{
-  worker_ = pool_.pop();
-  worker_->beginTask(func, arg);
-}
-
-void
-Thread::wait()
-{
-  worker_->wait();
-#if 0
-  delete worker_;
-#else
-  pool_.push(worker_);
-#endif
-  worker_ = NULL;
-}
-
-} // namespace
diff --git a/util/Thread.hh b/util/Thread.hh
deleted file mode 100644
index c107a8f1..00000000
--- a/util/Thread.hh
+++ /dev/null
@@ -1,48 +0,0 @@
-// OpenSTA, Static Timing Analyzer
-// Copyright (c) 2020, Parallax Software, Inc.
-// 
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-// 
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-// 
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-#ifndef STA_THREAD_H
-#define STA_THREAD_H
-
-#include "DisallowCopyAssign.hh"
-#include "ThreadWorker.hh"
-#include "ThreadPool.hh"
-
-namespace sta {
-
-// Basic thread class implemented using a pool of threads,
-// i.e., the threads are put to sleep when their task is done
-// and they are re-cycled for the next task.
-class Thread
-{
-public:
-  Thread();
-  // After calling start(), the caller must call wait() before
-  // destroying this object.
-  void beginTask(ThreadFunc func,
-		 void *arg);
-  void wait();
-
-private:
-  DISALLOW_COPY_AND_ASSIGN(Thread);
-
-  ThreadWorker *worker_;
-
-  static ThreadPool pool_;
-};
-
-} // namespace
-#endif
diff --git a/util/ThreadException.cc b/util/ThreadException.cc
deleted file mode 100644
index a0cfb6e1..00000000
--- a/util/ThreadException.cc
+++ /dev/null
@@ -1,38 +0,0 @@
-// OpenSTA, Static Timing Analyzer
-// Copyright (c) 2020, Parallax Software, Inc.
-// 
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-// 
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-// 
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-#include "Machine.hh"
-#include "StringUtil.hh"
-#include "ThreadException.hh"
-
-namespace sta {
-
-ThreadException::ThreadException(const char *filename,
-				 int line,
-				 int error) :
-  StaExceptionLine(filename, line),
-  error_(error)
-{
-}
-
-const char *
-ThreadException::what() const throw()
-{
-  const char *msg = strerror(error_);
-  return stringPrintTmp("Thread error in %s:%d %s.", filename_, line_, msg);
-}
-
-}
diff --git a/util/ThreadException.hh b/util/ThreadException.hh
deleted file mode 100644
index c5dafb57..00000000
--- a/util/ThreadException.hh
+++ /dev/null
@@ -1,41 +0,0 @@
-// OpenSTA, Static Timing Analyzer
-// Copyright (c) 2020, Parallax Software, Inc.
-// 
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-// 
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-// 
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-#ifndef STA_THREAD_EXCEPTION_H
-#define STA_THREAD_EXCEPTION_H
-
-#include "Error.hh"
-
-namespace sta {
-
-class ThreadException : public StaExceptionLine
-{
-public:
-  ThreadException(const char *filename,
-		  int line,
-		  int error);
-  virtual const char *what() const throw();
-
-protected:
-  int error_;
-};
-
-#define CheckThreadError(error) \
-  if (error != 0) \
-    throw ThreadException(__FILE__, __LINE__, error)
-
-} // namespace
-#endif
diff --git a/util/ThreadPool.cc b/util/ThreadPool.cc
deleted file mode 100644
index 6653afc5..00000000
--- a/util/ThreadPool.cc
+++ /dev/null
@@ -1,51 +0,0 @@
-// OpenSTA, Static Timing Analyzer
-// Copyright (c) 2020, Parallax Software, Inc.
-// 
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-// 
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-// 
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-#include "Machine.hh"
-#include "ThreadWorker.hh"
-#include "ThreadPool.hh"
-
-namespace sta {
-
-ThreadPool::~ThreadPool()
-{
-  threads_.deleteContentsClear();
-}
-
-ThreadWorker *
-ThreadPool::pop()
-{
-  lock_.lock();
-  if (!threads_.empty()) {
-    ThreadWorker *thread = threads_.back();
-    threads_.pop_back();
-    lock_.unlock();
-    return thread;
-  }
-  lock_.unlock();
-  // No threads in the pool, get a new one.
-  return new ThreadWorker;
-}
-
-void
-ThreadPool::push(ThreadWorker *thread)
-{
-  lock_.lock();
-  threads_.push_back(thread);
-  lock_.unlock();
-}
-
-} // namespace
diff --git a/util/ThreadPool.hh b/util/ThreadPool.hh
deleted file mode 100644
index b923f9aa..00000000
--- a/util/ThreadPool.hh
+++ /dev/null
@@ -1,45 +0,0 @@
-// OpenSTA, Static Timing Analyzer
-// Copyright (c) 2020, Parallax Software, Inc.
-// 
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-// 
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-// 
-// You should have received a copy of the GNU General Public License
-// along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-#ifndef STA_THREAD_POOL_H
-#define STA_THREAD_POOL_H
-
-#include "DisallowCopyAssign.hh"
-#include "Vector.hh"
-#include "Mutex.hh"
-
-namespace sta {
-
-class ThreadWorker;
-
-class ThreadPool
-{
-public:
-  ThreadPool() {}
-  ~ThreadPool();
-  // Create a new working thread if the pool is empty.
-  ThreadWorker *pop();
-  void push(ThreadWorker *thread);
-
-private:
-  DISALLOW_COPY_AND_ASSIGN(ThreadPool);
-
-  Vector<ThreadWorker*> threads_;
-  Mutex lock_;
-};
-
-} // namespace
-#endif