1 files changed, 7 insertions, 12 deletions
diff --git a/primes.py b/primes.py
index aff6697..7e83ea0 100644
--- a/primes.py
+++ b/primes.py
@@ -10,30 +10,25 @@ PRIMES = [
     115797848077099]
 
 def is_prime(n):
-    n = abs(n)
-    i = 2
-    while i <= math.sqrt(n):
+    if n % 2 == 0:
+        return False
+
+    sqrt_n = int(math.floor(math.sqrt(n)))
+    for i in range(3, sqrt_n + 1, 2):
         if n % i == 0:
             return False
-        i += 1
     return True
 
 def sequential():
     return list(map(is_prime, PRIMES))
 
 def with_process_pool_executor():
-    executor = futures.ProcessPoolExecutor(10)
-    try:
+    with futures.ProcessPoolExecutor(10) as executor:
         return list(executor.map(is_prime, PRIMES))
-    finally:
-        executor.shutdown()
 
 def with_thread_pool_executor():
-    executor = futures.ThreadPoolExecutor(10)
-    try:
+    with futures.ThreadPoolExecutor(10) as executor:
         return list(executor.map(is_prime, PRIMES))
-    finally:
-        executor.shutdown()
 
 def main():
     for name, fn in [('sequential', sequential),