[DS-2900] Java date format usage as static variable is not thread safe

dspace-api/src/main/java/org/dspace/app/statistics/StatisticsLoader.java

@@ -10,6 +10,7 @@ package org.dspace.app.statistics;
 import org.apache.commons.lang.time.DateUtils;
 import org.dspace.core.ConfigurationManager;
 
+import java.text.DateFormat;
 import java.util.*;
 import java.util.regex.Pattern;
 import java.util.regex.Matcher;
@@ -37,8 +38,8 @@ public class StatisticsLoader
     private static Pattern reportMonthlyPattern;
     private static Pattern reportGeneralPattern;
 
-    private static SimpleDateFormat monthlySDF;
+    private static ThreadLocal<DateFormat>  monthlySDF;
-    private static SimpleDateFormat generalSDF;
+    private static ThreadLocal<DateFormat>  generalSDF;
 
     // one time initialisation of the regex patterns and formatters we will use
     static
@@ -48,8 +49,19 @@ public class StatisticsLoader
         reportMonthlyPattern   = Pattern.compile("report-([0-9][0-9][0-9][0-9]-[0-9]+)\\.html");
         reportGeneralPattern   = Pattern.compile("report-general-([0-9]+-[0-9]+-[0-9]+)\\.html");
 
-        monthlySDF = new SimpleDateFormat("yyyy'-'M");
+        monthlySDF = new ThreadLocal<DateFormat>(){
-        generalSDF = new SimpleDateFormat("yyyy'-'M'-'dd");
+            @Override
+            protected DateFormat initialValue() {
+                return new SimpleDateFormat("yyyy'-'M");
+            }
+          };
+
+        generalSDF = new ThreadLocal<DateFormat>() {
+            @Override
+            protected DateFormat initialValue() {
+                return new SimpleDateFormat("yyyy'-'M'-'dd");
+            }
+        };
     }
 
     /**
@@ -81,7 +93,7 @@ public class StatisticsLoader
         {
             try
             {
-                dates[i] = monthlySDF.parse(date);
+                dates[i] = monthlySDF.get().parse(date);
             }
             catch (ParseException pe)
             {
@@ -228,7 +240,7 @@ public class StatisticsLoader
                 if (statsFile == null)
                 {
                     // See if it is a monthly analysis file
-                    statsFile = makeStatsFile(thisFile, analysisMonthlyPattern, monthlySDF);
+                    statsFile = makeStatsFile(thisFile, analysisMonthlyPattern, monthlySDF.get());
                     if (statsFile != null)
                     {
                         // If it is, add it to the map
@@ -240,7 +252,7 @@ public class StatisticsLoader
                 if (statsFile == null)
                 {
                     // See if it is a monthly report file
-                    statsFile = makeStatsFile(thisFile, reportMonthlyPattern, monthlySDF);
+                    statsFile = makeStatsFile(thisFile, reportMonthlyPattern, monthlySDF.get());
                     if (statsFile != null)
                     {
                         // If it is, add it to the map
@@ -252,7 +264,7 @@ public class StatisticsLoader
                 if (statsFile == null)
                 {
                     // See if it is a general analysis file
-                    statsFile = makeStatsFile(thisFile, analysisGeneralPattern, generalSDF);
+                    statsFile = makeStatsFile(thisFile, analysisGeneralPattern, generalSDF.get());
                     if (statsFile != null)
                     {
                         // If it is, ensure that we are pointing to the most recent file
@@ -267,7 +279,7 @@ public class StatisticsLoader
                 if (statsFile == null)
                 {
                     // See if it is a general report file
-                    statsFile = makeStatsFile(thisFile, reportGeneralPattern, generalSDF);
+                    statsFile = makeStatsFile(thisFile, reportGeneralPattern, generalSDF.get());
                     if (statsFile != null)
                     {
                         // If it is, ensure that we are pointing to the most recent file
@@ -297,7 +309,7 @@ public class StatisticsLoader
      * @param thisPattern
      * @param sdf
      */
-    private static StatsFile makeStatsFile(File thisFile, Pattern thisPattern, SimpleDateFormat sdf)
+    private static StatsFile makeStatsFile(File thisFile, Pattern thisPattern, DateFormat sdf)
     {
         Matcher matcher = thisPattern.matcher(thisFile.getName());
         if (matcher.matches())

dspace-api/src/main/java/org/dspace/checker/ResultsLogger.java

@@ -8,6 +8,7 @@
 package org.dspace.checker;
 
 import java.sql.SQLException;
+import java.text.DateFormat;
 import java.text.SimpleDateFormat;
 import java.util.Date;
 
@@ -38,9 +39,12 @@ public class ResultsLogger implements ChecksumResultsCollector
     /**
      * Utility date format.
      */
-    private static final SimpleDateFormat DATE_FORMAT = new SimpleDateFormat(
+    private static final ThreadLocal<DateFormat> DATE_FORMAT = new ThreadLocal<DateFormat>() {
-            "MM/dd/yyyy hh:mm:ss");
+        @Override
-
+        protected DateFormat initialValue() {
+            return new SimpleDateFormat("MM/dd/yyyy hh:mm:ss");
+        }
+    };
     /**
      * Date the current checking run started.
      */
@@ -61,7 +65,7 @@ public class ResultsLogger implements ChecksumResultsCollector
      */
     public ResultsLogger(Date startDt)
     {
-        LOG.info(msg("run-start-time") + ": " + DATE_FORMAT.format(startDt));
+        LOG.info(msg("run-start-time") + ": " + DATE_FORMAT.get().format(startDt));
     }
 
     /**
@@ -106,7 +110,7 @@ public class ResultsLogger implements ChecksumResultsCollector
         LOG.info(msg("previous-checksum") + ": " + info.getExpectedChecksum());
         LOG.info(msg("previous-checksum-date")
                 + ": "
-                + ((info.getProcessEndDate() != null) ? DATE_FORMAT.format(info
+                + ((info.getProcessEndDate() != null) ? DATE_FORMAT.get().format(info
                         .getProcessEndDate()) : "unknown"));
         LOG.info(msg("new-checksum") + ": " + info.getCurrentChecksum());
         LOG.info(msg("checksum-comparison-result") + ": "

dspace-api/src/main/java/org/dspace/eperson/Groomer.java

@@ -11,6 +11,7 @@ package org.dspace.eperson;
 import java.io.IOException;
 import java.sql.SQLException;
 import java.text.DateFormat;
+import java.text.SimpleDateFormat;
 import java.util.Calendar;
 import java.util.Date;
 import java.util.List;
@@ -28,7 +29,12 @@ import org.dspace.eperson.service.EPersonService;
  */
 public class Groomer
 {
-    private static final DateFormat dateFormat = DateFormat.getDateInstance(DateFormat.SHORT);
+    private static final ThreadLocal<DateFormat> dateFormat = new ThreadLocal<DateFormat>() {
+        @Override
+        protected DateFormat initialValue() {
+            return DateFormat.getDateInstance(DateFormat.SHORT);
+        }
+    };
 
     private static final EPersonService ePersonService = EPersonServiceFactory.getInstance().getEPersonService();
     /**
@@ -50,7 +56,7 @@ public class Groomer
 
         options.addOption("b", "last-used-before", true,
                 "date of last login was before this (for example:  "
-                        + dateFormat.format(Calendar.getInstance().getTime())
+                        + dateFormat.get().format(Calendar.getInstance().getTime())
                         + ')');
         options.addOption("d", "delete", false, "delete matching epersons");
 
@@ -102,7 +108,7 @@ public class Groomer
 
             Date before = null;
             try {
-                before = dateFormat.parse(command.getOptionValue('b'));
+                before = dateFormat.get().parse(command.getOptionValue('b'));
             } catch (java.text.ParseException ex) {
                 System.err.println(ex.getMessage());
                 System.exit(1);

dspace-api/src/main/java/org/dspace/statistics/util/StatisticsImporter.java

@@ -44,7 +44,12 @@ public class StatisticsImporter
     private static final Logger log = Logger.getLogger(StatisticsImporter.class);
 
     /** Date format (for solr) */
-    private static final SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
+    private static final ThreadLocal<DateFormat> dateFormat = new ThreadLocal<DateFormat>() {
+        @Override
+        protected DateFormat initialValue() {
+            return new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
+        }
+    };
     protected final SolrLoggerService solrLoggerService = StatisticsServiceFactory.getInstance().getSolrLoggerService();
 
     /** Solr server connection */
@@ -209,7 +214,7 @@ public class StatisticsImporter
 //                uuid = parts[0];
                 action = parts[1];
                 id = parts[2];
-                date = dateFormat.parse(parts[3]);
+                date = dateFormat.get().parse(parts[3]);
                 user = parts[4];
                 ip = parts[5];
 

dspace-api/src/main/java/org/dspace/statistics/util/StatisticsImporterElasticSearch.java

@@ -35,6 +35,7 @@ import org.elasticsearch.common.xcontent.XContentFactory;
 
 
 import java.io.*;
+import java.text.DateFormat;
 import java.text.DecimalFormat;
 import java.text.SimpleDateFormat;
 import java.util.*;
@@ -51,7 +52,12 @@ public class StatisticsImporterElasticSearch {
     private static final Logger log = Logger.getLogger(StatisticsImporterElasticSearch.class);
 
     /** Date format */
-    private static SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
+    private static ThreadLocal<DateFormat> dateFormat = new ThreadLocal<DateFormat>() {
+        @Override
+        protected DateFormat initialValue() {
+            return new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
+        }
+    };
 
     //TODO ES Client
 
@@ -131,7 +137,7 @@ public class StatisticsImporterElasticSearch {
 //                uuid = parts[0];
                 action = parts[1];
                 id = parts[2];
-                date = dateFormat.parse(parts[3]);
+                date = dateFormat.get().parse(parts[3]);
                 user = parts[4];
                 ip = parts[5];
 

dspace-api/src/main/java/org/dspace/util/MultiFormatDateParser.java

@@ -47,11 +47,17 @@ public class MultiFormatDateParser
     private static final TimeZone UTC_ZONE = TimeZone.getTimeZone("UTC");
 
     /** Format for displaying a result of testing. */
-    private static final DateFormat formatter;
+    private static final ThreadLocal<DateFormat> formatter;
     static
     {
-        formatter = SimpleDateFormat.getDateTimeInstance();
+        formatter = new ThreadLocal<DateFormat>(){
-        formatter.setTimeZone(UTC_ZONE);
+        @Override
+        protected DateFormat initialValue() {
+            DateFormat dateTimeInstance = SimpleDateFormat.getDateTimeInstance();
+            dateTimeInstance.setTimeZone(UTC_ZONE);
+            return dateTimeInstance;
+        }
+      };
     }
 
     @Inject
@@ -156,7 +162,7 @@ public class MultiFormatDateParser
             System.out.println("Did not match any pattern.");
         else
         {
-            System.out.println(formatter.format(result));
+            System.out.println(formatter.get().format(result));
         }
     }
 

dspace-api/src/main/java/org/dspace/util/SolrImportExport.java

@@ -42,14 +42,34 @@ import java.util.*;
 public class SolrImportExport
 {
 
-	private static final DateFormat SOLR_DATE_FORMAT = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
+	private static final ThreadLocal<DateFormat> SOLR_DATE_FORMAT;
-	private static final DateFormat SOLR_DATE_FORMAT_NO_MS = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
+	private static final ThreadLocal<DateFormat> SOLR_DATE_FORMAT_NO_MS;
-	private static final DateFormat EXPORT_DATE_FORMAT = new SimpleDateFormat("yyyy-MM");
+	private static final ThreadLocal<DateFormat> EXPORT_DATE_FORMAT;
 
 	static
 	{
-		SOLR_DATE_FORMAT.setTimeZone(TimeZone.getTimeZone("UTC"));
+		SOLR_DATE_FORMAT = new ThreadLocal<DateFormat>(){
-		EXPORT_DATE_FORMAT.setTimeZone(TimeZone.getDefault());
+			@Override
+			protected DateFormat initialValue() {
+				SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
+				simpleDateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
+				return simpleDateFormat;
+			}
+		  };
+		SOLR_DATE_FORMAT_NO_MS = new ThreadLocal<DateFormat>(){
+					@Override
+					protected DateFormat initialValue() {
+						return new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
+					}
+				  };
+		EXPORT_DATE_FORMAT = new ThreadLocal<DateFormat>() {
+			@Override
+			protected DateFormat initialValue() {
+				SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM");
+				simpleDateFormat.setTimeZone(TimeZone.getDefault());
+				return simpleDateFormat;
+			}
+		};
 	}
 
 	private static final String ACTION_OPTION = "a";
@@ -550,7 +570,7 @@ public class SolrImportExport
 		query.setRows(0);
 		query.setFacet(true);
 		query.add(FacetParams.FACET_RANGE, timeField);
-		query.add(FacetParams.FACET_RANGE_START, SOLR_DATE_FORMAT.format(earliestTimestamp) + "/MONTH");
+		query.add(FacetParams.FACET_RANGE_START, SOLR_DATE_FORMAT.get().format(earliestTimestamp) + "/MONTH");
 		query.add(FacetParams.FACET_RANGE_END, "NOW/MONTH+1MONTH");
 		query.add(FacetParams.FACET_RANGE_GAP, "+1MONTH");
 		query.setFacetMinCount(1);
@@ -562,7 +582,7 @@ public class SolrImportExport
 			String monthStart = monthFacet.getValue();
 			try
 			{
-				monthStartDate = SOLR_DATE_FORMAT_NO_MS.parse(monthStart);
+				monthStartDate = SOLR_DATE_FORMAT_NO_MS.get().parse(monthStart);
 			}
 			catch (java.text.ParseException e)
 			{
@@ -622,7 +642,7 @@ public class SolrImportExport
 			// other acceptable value: a number, specifying how many days back to export
 			days = Integer.valueOf(lastValue); // TODO check value?
 		}
-		return timeField + ":[NOW/DAY-" + days + "DAYS TO " + SOLR_DATE_FORMAT.format(new Date()) + "]";
+		return timeField + ":[NOW/DAY-" + days + "DAYS TO " + SOLR_DATE_FORMAT.get().format(new Date()) + "]";
 	}
 
 	/**
@@ -657,7 +677,7 @@ public class SolrImportExport
 		}
 		return indexName
 				       + "_export_"
-					   + EXPORT_DATE_FORMAT.format(exportStart)
+					   + EXPORT_DATE_FORMAT.get().format(exportStart)
 					   + (StringUtils.isNotBlank(exportFileNumber) ? "_" + exportFileNumber : "")
 				       + ".csv";
 	}

dspace-oai/src/main/java/org/dspace/xoai/services/impl/cache/DSpaceXOAILastCompilationCacheService.java

@@ -13,6 +13,7 @@ import org.dspace.xoai.services.api.cache.XOAILastCompilationCacheService;
 
 import java.io.File;
 import java.io.IOException;
+import java.text.DateFormat;
 import java.text.ParseException;
 import java.text.SimpleDateFormat;
 import java.util.Date;
@@ -20,7 +21,12 @@ import java.util.Date;
 
 public class DSpaceXOAILastCompilationCacheService implements XOAILastCompilationCacheService {
 
-    private static final SimpleDateFormat format = new SimpleDateFormat();
+    private static final ThreadLocal<DateFormat> format = new ThreadLocal<DateFormat>(){
+                            @Override
+                            protected DateFormat initialValue() {
+                                return new SimpleDateFormat();
+                            }
+                          };
     private static final String DATEFILE = File.separator + "date.file";
 
     private static File file = null;
@@ -47,7 +53,7 @@ public class DSpaceXOAILastCompilationCacheService implements XOAILastCompilatio
 
     @Override
     public void put(Date date) throws IOException {
-        FileUtils.write(getFile(), format.format(date));
+        FileUtils.write(getFile(), format.get().format(date));
     }
 
 
@@ -57,7 +63,7 @@ public class DSpaceXOAILastCompilationCacheService implements XOAILastCompilatio
     @Override
     public Date get() throws IOException {
         try {
-            return format.parse(FileUtils.readFileToString(getFile()).trim());
+            return format.get().parse(FileUtils.readFileToString(getFile()).trim());
         } catch (ParseException e) {
             throw new IOException(e);
         }

dspace-xmlui/src/main/java/org/dspace/app/xmlui/aspect/artifactbrowser/StatisticsViewer.java

@@ -55,8 +55,18 @@ public class StatisticsViewer extends AbstractDSpaceTransformer implements Cache
     private static final Message T_empty_title   = message("xmlui.ArtifactBrowser.StatisticsViewer.no_report.title");
     private static final Message T_empty_text    = message("xmlui.ArtifactBrowser.StatisticsViewer.no_report.text");
 
-    private static final SimpleDateFormat sdfDisplay = new SimpleDateFormat("MM'/'yyyy");
+    private static final ThreadLocal<DateFormat> sdfDisplay = new ThreadLocal<DateFormat>(){
-    private static final SimpleDateFormat sdfLink    = new SimpleDateFormat("yyyy'-'M");
+                @Override
+                protected DateFormat initialValue() {
+                    return new SimpleDateFormat("MM'/'yyyy");
+                }
+              };
+    private static final ThreadLocal<DateFormat> sdfLink    = new ThreadLocal<DateFormat>(){
+                @Override
+                protected DateFormat initialValue() {
+                    return new SimpleDateFormat("yyyy'-'M");
+                }
+              };
 
     private boolean initialised = false;
     private String reportDate = null;
@@ -165,8 +175,8 @@ public class StatisticsViewer extends AbstractDSpaceTransformer implements Cache
             HashMap<String, String> params = new HashMap<String, String>();
             for (Date date : monthlyDates)
             {
-                params.put("date", sdfLink.format(date));
+                params.put("date", sdfLink.get().format(date));
-                statList.addItemXref(super.generateURL("statistics", params), sdfDisplay.format(date));
+                statList.addItemXref(super.generateURL("statistics", params), sdfDisplay.get().format(date));
             }
         }
     }

dspace-xmlui/src/main/java/org/dspace/app/xmlui/aspect/statisticsElasticSearch/CSVOutputter.java

@@ -39,6 +39,7 @@ import org.xml.sax.SAXException;
 import javax.servlet.http.HttpServletResponse;
 import java.io.IOException;
 import java.sql.SQLException;
+import java.text.DateFormat;
 import java.text.SimpleDateFormat;
 import java.util.*;
 
@@ -49,7 +50,12 @@ import java.util.*;
 public class CSVOutputter extends AbstractReader implements Recyclable 
 {
     protected static final Logger log = Logger.getLogger(CSVOutputter.class);
-    private static SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
+    private static ThreadLocal<DateFormat> dateFormat = new ThreadLocal<DateFormat>(){
+                    @Override
+                    protected DateFormat initialValue() {
+                        return new SimpleDateFormat("yyyy-MM-dd");
+                    }
+                  };
 
     protected Response response;
     protected Request request;
@@ -230,7 +236,7 @@ public class CSVOutputter extends AbstractReader implements Recyclable
 
         for(DateHistogramFacet.Entry histogramEntry : monthlyFacetEntries) {
             Date facetDate = new Date(histogramEntry.getTime());
-            writer.writeNext(new String[]{dateFormat.format(facetDate), String.valueOf(histogramEntry.getCount())});
+            writer.writeNext(new String[]{dateFormat.get().format(facetDate), String.valueOf(histogramEntry.getCount())});
         }
     }
 

dspace-xmlui/src/main/java/org/dspace/app/xmlui/aspect/statisticsElasticSearch/ElasticSearchStatsViewer.java

@@ -37,6 +37,7 @@ import org.elasticsearch.search.facet.datehistogram.DateHistogramFacet;
 import org.elasticsearch.search.facet.terms.TermsFacet;
 
 import java.sql.SQLException;
+import java.text.DateFormat;
 import java.text.SimpleDateFormat;
 import java.util.*;
 import java.util.List;
@@ -51,8 +52,18 @@ public class ElasticSearchStatsViewer extends AbstractDSpaceTransformer {
     
     public static final String elasticStatisticsPath = "stats";
 
-    private static SimpleDateFormat monthAndYearFormat = new SimpleDateFormat("MMMMM yyyy");
+    private static ThreadLocal<DateFormat> monthAndYearFormat = new ThreadLocal<DateFormat>(){
-    private static SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
+                        @Override
+                        protected DateFormat initialValue() {
+                            return new SimpleDateFormat("MMMMM yyyy");
+                        }
+                      };
+    private static ThreadLocal<DateFormat> dateFormat = new ThreadLocal<DateFormat>(){
+                        @Override
+                        protected DateFormat initialValue() {
+                            return new SimpleDateFormat("yyyy-MM-dd");
+                        }
+                      };
 
     private static Client client;
     private static Division division;
@@ -157,10 +168,10 @@ public class ElasticSearchStatsViewer extends AbstractDSpaceTransformer {
                 division.addPara("Showing Data ( " + dateRange + " )");
                 division.addHidden("timeRangeString").setValue("Data Range: " + dateRange);
                 if(dateStart != null) {
-                    division.addHidden("dateStart").setValue(dateFormat.format(dateStart));
+                    division.addHidden("dateStart").setValue(dateFormat.get().format(dateStart));
                 }
                 if(dateEnd != null) {
-                    division.addHidden("dateEnd").setValue(dateFormat.format(dateEnd));
+                    division.addHidden("dateEnd").setValue(dateFormat.get().format(dateEnd));
                 }
 
                 showAllReports();
@@ -179,21 +190,21 @@ public class ElasticSearchStatsViewer extends AbstractDSpaceTransformer {
                 
                 String dateRange = "";
                 if(dateStart != null && dateEnd != null) {
-                    dateRange = "from: "+dateFormat.format(dateStart) + " to: "+dateFormat.format(dateEnd);
+                    dateRange = "from: "+dateFormat.get().format(dateStart) + " to: "+dateFormat.get().format(dateEnd);
                 } else if (dateStart != null && dateEnd == null) {
-                    dateRange = "starting from: "+dateFormat.format(dateStart);
+                    dateRange = "starting from: "+dateFormat.get().format(dateStart);
                 } else if(dateStart == null && dateEnd != null) {
-                    dateRange = "ending with: "+dateFormat.format(dateEnd);
+                    dateRange = "ending with: "+dateFormat.get().format(dateEnd);
                 } else if(dateStart == null && dateEnd == null) {
                     dateRange = "All Data Available";
                 }
                 division.addPara("Showing Data ( " + dateRange + " )");
                 division.addHidden("timeRangeString").setValue(dateRange);
                 if(dateStart != null) {
-                    division.addHidden("dateStart").setValue(dateFormat.format(dateStart));
+                    division.addHidden("dateStart").setValue(dateFormat.get().format(dateStart));
                 }
                 if(dateEnd != null) {
-                    division.addHidden("dateEnd").setValue(dateFormat.format(dateEnd));
+                    division.addHidden("dateEnd").setValue(dateFormat.get().format(dateEnd));
                 }
 
 
@@ -261,10 +272,10 @@ public class ElasticSearchStatsViewer extends AbstractDSpaceTransformer {
         calendar.add(Calendar.MONTH, -1);
 
         calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMinimum(Calendar.DAY_OF_MONTH));
-        String lowerBound = dateFormat.format(calendar.getTime());
+        String lowerBound = dateFormat.get().format(calendar.getTime());
 
         calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMaximum(Calendar.DAY_OF_MONTH));
-        String upperBound = dateFormat.format(calendar.getTime());
+        String upperBound = dateFormat.get().format(calendar.getTime());
 
         log.info("Lower:"+lowerBound+" -- Upper:"+upperBound);
         
@@ -282,7 +293,7 @@ public class ElasticSearchStatsViewer extends AbstractDSpaceTransformer {
         calendar.add(Calendar.MONTH, -1);
 
         calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMinimum(Calendar.DAY_OF_MONTH));
-        return monthAndYearFormat.format(calendar.getTime());
+        return monthAndYearFormat.get().format(calendar.getTime());
     }
     
     public SearchRequestBuilder facetedQueryBuilder(FacetBuilder facet) throws WingException{
@@ -398,7 +409,7 @@ public class ElasticSearchStatsViewer extends AbstractDSpaceTransformer {
         for(DateHistogramFacet.Entry histogramEntry : monthlyFacetEntries) {
             Row dataRow = monthlyTable.addRow();
             Date facetDate = new Date(histogramEntry.getTime());
-            dataRow.addCell("date", Cell.ROLE_DATA,"date").addContent(dateFormat.format(facetDate));
+            dataRow.addCell("date", Cell.ROLE_DATA,"date").addContent(dateFormat.get().format(facetDate));
             dataRow.addCell("count", Cell.ROLE_DATA,"count").addContent("" + histogramEntry.getCount());
         }
     }

dspace-xmlui/src/main/java/org/dspace/app/xmlui/aspect/statisticsElasticSearch/ReportGenerator.java

@@ -38,7 +38,12 @@ public class ReportGenerator
      * The minimum date for the from or to field to be. (e.g. The beginning of DSpace)
      */
     private static String MINIMUM_DATE = "2008-01-01";
-    private static SimpleDateFormat dateFormat = new SimpleDateFormat("MM/dd/yyyy");
+    private static ThreadLocal<DateFormat> dateFormat = new ThreadLocal<DateFormat>() {
+        @Override
+        protected DateFormat initialValue() {
+            return new SimpleDateFormat("MM/dd/yyyy");
+        }
+    };
 
     // perfect input is 2008-01-22, an alternate format is 01/22/2008
     static String[] formatStrings = {"MM/dd/yyyy", "yyyy-MM-dd"};
@@ -54,7 +59,7 @@ public class ReportGenerator
     
     public String getDateStartFormated() {
         try {
-            return dateFormat.format(dateStart);
+            return dateFormat.get().format(dateStart);
         } catch (Exception e) {
             return "";
         }
@@ -89,7 +94,7 @@ public class ReportGenerator
     
     public String getDateEndFormatted() {
         try {
-            return dateFormat.format(dateEnd);
+            return dateFormat.get().format(dateEnd);
         } catch (Exception e) {
             return "";
         }