Updated memory attribute to use peak_rss for calculation

plugins/nf-co2footprint/src/main/nextflow/co2footprint/CO2FootprintFactory.groovy

@@ -174,22 +174,17 @@ class CO2FootprintFactory implements TraceObserverFactory {
         }
         // TODO how to handle double, Double datatypes for ceiling?
         if ( cpu_usage == 0.0 ) {
-            warnings << "The reported CPU usage is 0.0 for at last one task!"
+            warnings << "The reported CPU usage is 0.0 for at least one task!"
         }
         Double uc = cpu_usage / (100.0 * nc) as Double
 
         /**
          * Factors of memory power usage
          */
-        // nm: size of memory available [GB] -> requested memory
-        Long memory = trace.get('memory') as Long
-        if ( memory == null ) {
-            // TODO if 'memory' not set, returns null, hande somehow?
-            log.error "TraceRecord field 'memory' is not set!"
-            System.exit(1)
-        }
-        Double nm = memory/1000000000 as Double
-        // TODO handle if more memory/cpus used than requested?
+        // nm: (Peak resident set size i.e. high water mark) [GB] -> maximum amount of physical memory (RAM) that the process had in use at any point during its execution.
+        Double memory = trace.get('peak_rss') as Double
+
+        Double nm = memory/(1024*1024*1024) as Double
 
         // Pm: power draw of memory [W per GB]
         Double pm  = config.getPowerdrawMem()