diff --git a/aksw-commons-io-parent/aksw-commons-io-hadoop/src/main/java/org/aksw/commons/io/hadoop/binseach/v2/BinSearchCacheFixed.java b/aksw-commons-io-parent/aksw-commons-io-hadoop/src/main/java/org/aksw/commons/io/hadoop/binseach/v2/BinSearchCacheFixed.java
index 41804227..f69b75bd 100644
--- a/aksw-commons-io-parent/aksw-commons-io-hadoop/src/main/java/org/aksw/commons/io/hadoop/binseach/v2/BinSearchCacheFixed.java
+++ b/aksw-commons-io-parent/aksw-commons-io-hadoop/src/main/java/org/aksw/commons/io/hadoop/binseach/v2/BinSearchCacheFixed.java
@@ -5,6 +5,10 @@
 import java.util.Map.Entry;
 import java.util.NavigableMap;
 import java.util.TreeMap;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+
+import org.aksw.commons.util.lock.LockUtils;
 
 class BinSearchCacheFixed
     implements BinSearchCache
@@ -13,6 +17,9 @@ class BinSearchCacheFixed
     protected NavigableMap<Long, Long> fixedDispositions;
     protected Map<Long, HeaderRecord> fixedHeaders;
 
+    protected ReadWriteLock dispositionLock = new ReentrantReadWriteLock();
+    protected ReadWriteLock headerLock = new ReentrantReadWriteLock();
+
     public BinSearchCacheFixed() {
         super();
         this.fixedDispositions = new TreeMap<>();
@@ -21,64 +28,72 @@ public BinSearchCacheFixed() {
 
     @Override
     public long getDisposition(long position) {
-        long result = -1;
-        if (fixedHeaders.containsKey(position)) {
-            result = position;
-        } else {
-            Entry<Long, Long> e = fixedDispositions.floorEntry(position);
-            if (e != null) {
-                // long from = e.getKey();
-                long to = e.getValue();
-                if (position <= to) {
-                    result = to;
+        return LockUtils.runWithLock(dispositionLock.readLock(), () -> {
+            long result = -1;
+            if (fixedHeaders.containsKey(position)) {
+                result = position;
+            } else {
+                Entry<Long, Long> e = fixedDispositions.floorEntry(position);
+                if (e != null) {
+                    // long from = e.getKey();
+                    long to = e.getValue();
+                    if (position <= to) {
+                        result = to;
+                    }
                 }
             }
-        }
-        return result;
+            return result;
+        });
     }
 
     @Override
     public void setDisposition(long from, long to) {
-        Entry<Long, Long> e = fixedDispositions.floorEntry(from);
-        if (e != null) {
-            long cachedFrom = e.getKey();
-            long cachedTo = e.getValue();
+        LockUtils.runWithLock(dispositionLock.writeLock(), () -> {
+            Entry<Long, Long> e = fixedDispositions.floorEntry(from);
+            if (e != null) {
+                long cachedFrom = e.getKey();
+                long cachedTo = e.getValue();
 
-            // issues to check for:
-            // TODO cached range overlaps with starting point (cachedTo > from)
-            if (cachedTo > to) {
-                // new:       [        ]
-                // cached:    [    ]
-                throw new IllegalStateException(String.format("The upper endoint overlaps with an existing entry: [%d, %d] -> [%d, %d]", from, to, cachedFrom, cachedTo));
-            } else if (cachedTo == to) {
-                // Update an existing entry with a lower boundary
-                if (from < cachedFrom) {
-                    fixedDispositions.remove(cachedFrom);
+                // issues to check for:
+                // TODO cached range overlaps with starting point (cachedTo > from)
+                if (cachedTo > to) {
+                    // new:       [        ]
+                    // cached:    [    ]
+                    throw new IllegalStateException(String.format("The upper endoint overlaps with an existing entry: [%d, %d] -> [%d, %d]", from, to, cachedFrom, cachedTo));
+                } else if (cachedTo == to) {
+                    // Update an existing entry with a lower boundary
+                    if (from < cachedFrom) {
+                        fixedDispositions.remove(cachedFrom);
+                        fixedDispositions.put(from, to);
+                    }
+                } else { // to < cachedTo
+                    // Sanity check: New's lower endpoint must not overlap
+                    // new:          [   ]
+                    // existing: [    ]
+                    if (from <= cachedTo) {
+                        throw new IllegalStateException(String.format("Overlap with an existing entry: [%d, %d] -> [%d, %d]", from, to, cachedFrom, cachedTo));
+                    }
                     fixedDispositions.put(from, to);
                 }
-            } else { // to < cachedTo
-                // Sanity check: New's lower endpoint must not overlap
-                // new:          [   ]
-                // existing: [    ]
-                if (from <= cachedTo) {
-                    throw new IllegalStateException(String.format("Overlap with an existing entry: [%d, %d] -> [%d, %d]", from, to, cachedFrom, cachedTo));
-                }
+            } else {
                 fixedDispositions.put(from, to);
             }
-        } else {
-            fixedDispositions.put(from, to);
-        }
+        });
     }
 
     @Override
     public HeaderRecord getHeader(long position) {
-        HeaderRecord result = fixedHeaders.get(position);
-        return result;
+        return LockUtils.runWithLock(headerLock.readLock(), () -> {
+            HeaderRecord result = fixedHeaders.get(position);
+            return result;
+        });
     }
 
     @Override
     public void setHeader(HeaderRecord headerRecord) {
-        // HeaderRecord headerRecord = new HeaderRecord(position, disposition, header, isDataConsumed);
-        fixedHeaders.put(headerRecord.position(), headerRecord);
+        LockUtils.runWithLock(headerLock.writeLock(), () -> {
+            // HeaderRecord headerRecord = new HeaderRecord(position, disposition, header, isDataConsumed);
+            fixedHeaders.put(headerRecord.position(), headerRecord);
+        });
     }
 }
diff --git a/aksw-commons-io-parent/aksw-commons-io-hadoop/src/main/java/org/aksw/commons/io/hadoop/binseach/v2/BinSearchUtils.java b/aksw-commons-io-parent/aksw-commons-io-hadoop/src/main/java/org/aksw/commons/io/hadoop/binseach/v2/BinSearchUtils.java
index 4c9068ae..d8d60557 100644
--- a/aksw-commons-io-parent/aksw-commons-io-hadoop/src/main/java/org/aksw/commons/io/hadoop/binseach/v2/BinSearchUtils.java
+++ b/aksw-commons-io-parent/aksw-commons-io-hadoop/src/main/java/org/aksw/commons/io/hadoop/binseach/v2/BinSearchUtils.java
@@ -73,7 +73,7 @@ public static InputStream configureStream(
                     new ReadableByteChannelForLinesMatchingPrefix(
                             SeekableInputStreams.wrap(in), scanState));
         } else {
-            System.err.println("NO MATCH for " + new String(prefix));
+            // System.err.println("NO MATCH for " + new String(prefix));
             in.close();
             result = InputStream.nullInputStream(); // ReadableChannels.newInputStream(ReadableChannels.limit(in, 0));
         }