use US locale to format strings

This is especially important for all strings that are
passed to gnuplot. Because gnuplot uses the US locale
during parsing.

data-store/src/main/java/org/lucares/pdb/datastore/lang/SyntaxException.java

@@ -1,5 +1,7 @@
 package org.lucares.pdb.datastore.lang;
 
+import java.util.Locale;
+
 import org.antlr.v4.runtime.ParserRuleContext;
 
 public class SyntaxException extends RuntimeException {
@@ -27,7 +29,8 @@ public class SyntaxException extends RuntimeException {
     private static String generateMessage(final int lineStart, final int startIndex, final int lineStop,
             final int stopIndex) {
 
-        return String.format("line=%d, start=%d, to line=%d stop=%d", lineStart, startIndex, lineStop, stopIndex);
+        return String.format(Locale.US, "line=%d, start=%d, to line=%d stop=%d", lineStart, startIndex, lineStop,
+                stopIndex);
     }
 
     public int getLineStart() {

pdb-plotting/src/main/java/org/lucares/recommind/logs/AxisSettings.java

@@ -1,6 +1,7 @@
 package org.lucares.recommind.logs;
 
 import java.util.List;
+import java.util.Locale;
 
 import org.apache.commons.lang3.StringUtils;
 
@@ -162,7 +163,7 @@ public class AxisSettings {
     }
 
     private void appendfln(final StringBuilder builder, final String format, final Object... args) {
-        builder.append(String.format(format + "\n", args));
+        builder.append(String.format(Locale.US, format + "\n", args));
     }
 
     @Override

pdb-plotting/src/main/java/org/lucares/recommind/logs/Plotter.java

@@ -10,6 +10,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Locale;
 import java.util.UUID;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -209,7 +210,7 @@ public class Plotter {
 
         final int values = csvSummary.getValues();
         result.append(" (");
-        result.append(String.format("%,d", values));
+        result.append(String.format(Locale.US, "%,d", values));
         result.append(")");
 
         return result.toString();

performanceDb/src/main/java/org/lucares/performance/db/PdbExport.java

@@ -15,6 +15,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Locale;
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.stream.Stream;
 import java.util.zip.GZIPOutputStream;
@@ -90,7 +91,8 @@ public class PdbExport {
                         writer.flush();
                         writer.close();
                     }
-                    exportFile = backupDir.resolve(String.format("%s.%05d.pdb.gz", datePrefix, exportFileCounter++));
+                    exportFile = backupDir
+                            .resolve(String.format(Locale.US, "%s.%05d.pdb.gz", datePrefix, exportFileCounter++));
                     exportFiles.add(exportFile);
                     writer = createWriter(exportFile);
                     LOGGER.info("new export file: {}", exportFile);
@@ -128,8 +130,9 @@ public class PdbExport {
                             final long end = System.currentTimeMillis();
                             final long duration = end - begin;
                             final long entriesPerSecond = (long) (chunk / (duration / 1000.0));
-                            LOGGER.info("progress: {} - {} entries/s + duration {}", String.format("%,d", count),
-                                    String.format("%,d", entriesPerSecond), duration);
+                            LOGGER.info("progress: {} - {} entries/s + duration {}",
+                                    String.format(Locale.US, "%,d", count),
+                                    String.format(Locale.US, "%,d", entriesPerSecond), duration);
                             begin = System.currentTimeMillis();
                         }
                     }

performanceDb/src/main/java/org/lucares/performance/db/PerformanceDb.java

@@ -7,6 +7,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Locale;
 import java.util.Optional;
 import java.util.concurrent.ArrayBlockingQueue;
 import java.util.concurrent.ExecutorService;
@@ -120,7 +121,7 @@ public class PerformanceDb implements AutoCloseable {
                             final long duration = end - lastSync;
                             final long entriesPerSecond = (long) (insertionsSinceLastSync / (duration / 1000.0));
 
-                            METRICS_LOGGER.debug(String.format("inserting %d/s ; total: %,d; last: %s",
+                            METRICS_LOGGER.debug(String.format(Locale.US, "inserting %d/s ; total: %,d; last: %s",
                                     entriesPerSecond, count, entry));
 
                             lastSync = System.currentTimeMillis();