diff --git a/tools/cldr-code/src/main/java/org/unicode/cldr/test/TestCache.java b/tools/cldr-code/src/main/java/org/unicode/cldr/test/TestCache.java
index 022370ad85b..d5cbfdd9669 100644
--- a/tools/cldr-code/src/main/java/org/unicode/cldr/test/TestCache.java
+++ b/tools/cldr-code/src/main/java/org/unicode/cldr/test/TestCache.java
@@ -2,11 +2,12 @@
 
 import com.google.common.cache.Cache;
 import com.google.common.cache.CacheBuilder;
-import com.google.common.collect.ImmutableList;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map.Entry;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ExecutionException;
+import java.util.logging.Level;
 import java.util.logging.Logger;
 import org.unicode.cldr.test.CheckCLDR.CheckStatus;
 import org.unicode.cldr.test.CheckCLDR.Options;
@@ -60,12 +61,21 @@ public void check(String path, List<CheckStatus> result, String value) {
              */
             result.clear();
             Pair<String, String> key = new Pair<>(path, value);
-            List<CheckStatus> cachedResult = pathCache.get(key);
+            List<CheckStatus> cachedResult =
+                    pathCache.computeIfAbsent(
+                            key,
+                            (Pair<String, String> k) -> {
+                                List<CheckStatus> l = new ArrayList<CheckStatus>();
+                                cc.check(
+                                        k.getFirst(),
+                                        file.getFullXPath(k.getFirst()),
+                                        k.getSecond(),
+                                        options,
+                                        l);
+                                return l;
+                            });
             if (cachedResult != null) {
                 result.addAll(cachedResult);
-            } else {
-                cc.check(path, file.getFullXPath(path), value, options, result);
-                pathCache.put(key, ImmutableList.copyOf(result));
             }
         }
 
@@ -88,6 +98,7 @@ public List<CheckStatus> getPossibleProblems() {
     private Cache<CheckCLDR.Options, TestResultBundle> testResultCache =
             CacheBuilder.newBuilder()
                     .maximumSize(CLDRConfig.getInstance().getProperty("CLDR_TESTCACHE_SIZE", 12))
+                    .concurrencyLevel(1)
                     .softValues()
                     .build();
 
@@ -96,16 +107,13 @@ public List<CheckStatus> getPossibleProblems() {
     private String nameMatcher = ".*";
 
     /** Get the bundle for this test */
-    public TestResultBundle getBundle(CheckCLDR.Options options) {
-        TestResultBundle b = testResultCache.getIfPresent(options);
-        if (b != null) {
-            logger.finest(() -> this + " Bundle refvalid: " + options);
-        }
-        if (b == null) {
-            // ElapsedTimer et = new ElapsedTimer("New test bundle " + locale + " opt " + options);
-            b = new TestResultBundle(options);
-            // System.err.println(et.toString());
-            testResultCache.put(options, b);
+    public TestResultBundle getBundle(final CheckCLDR.Options options) {
+        TestResultBundle b;
+        try {
+            b = testResultCache.get(options, () -> new TestResultBundle(options));
+        } catch (ExecutionException e) {
+            logger.log(Level.SEVERE, e, () -> "Failed to load " + options);
+            throw new RuntimeException(e);
         }
         return b;
     }