在我的应用程序的某些部分，我将一个 17MB 的日志文件解析为一个列表结构——每行一个 LogEntry。大约有 100K 行/日志条目，这意味着大约。每行 170 个字节。令我惊讶的是，我用尽了堆空间，即使我指定 128MB（256MB 似乎足够了）。10MB 的文本如何变成一个对象列表导致空间增加十倍？
我知道 String 对象使用的空间量至少是 ANSI 文本（Unicode，一个字符 = 2 个字节）的两倍，但这至少消耗了四倍。
我正在寻找的是 n LogEntries 的 ArrayList 将消耗多少的近似值，或者我的方法可能如何创建使情况恶化的无关对象 （请参阅下面的评论String.trim()）
这是我的 LogEntry 类的数据部分
public class LogEntry {
private Long id;
private String system, version, environment, hostName, userId, clientIP, wsdlName, methodName;
private Date timestamp;
private Long milliSeconds;
private Map<String, String> otherProperties;
这是阅读的部分
public List<LogEntry> readLogEntriesFromFile(File f) throws LogImporterException {
CSVReader reader;
final String ISO_8601_DATE_PATTERN = "yyyy-MM-dd HH:mm:ss,SSS";
List<LogEntry> logEntries = new ArrayList<LogEntry>();
String[] tmp;
try {
int lineNumber = 0;
final char DELIM = ';';
reader = new CSVReader(new InputStreamReader(new FileInputStream(f)), DELIM);
while ((tmp = reader.readNext()) != null) {
lineNumber++;
if (tmp.length < LogEntry.getRequiredNumberOfAttributes()) {
String tmpString = concat(tmp);
if (tmpString.trim().isEmpty()) {
logger.debug("Empty string");
} else {
logger.error(String.format(
"Invalid log format in %s:L%s. Not enough attributes (%d/%d). Was %s . Continuing ...",
f.getAbsolutePath(), lineNumber, tmp.length, LogEntry.getRequiredNumberOfAttributes(), tmpString)
);
}
continue;
}
List<String> values = new ArrayList<String>(Arrays.asList(tmp));
String system, version, environment, hostName, userId, wsdlName, methodName;
Date timestamp;
Long milliSeconds;
Map<String, String> otherProperties;
system = values.remove(0);
version = values.remove(0);
environment = values.remove(0);
hostName = values.remove(0);
userId = values.remove(0);
String clientIP = values.remove(0);
wsdlName = cleanLogString(values.remove(0));
methodName = cleanLogString(stripNormalPrefixes(values.remove(0)));
timestamp = new SimpleDateFormat(ISO_8601_DATE_PATTERN).parse(values.remove(0));
milliSeconds = Long.parseLong(values.remove(0));
/* remaining properties are the key-value pairs */
otherProperties = parseOtherProperties(values);
logEntries.add(new LogEntry(system, version, environment, hostName, userId, clientIP,
wsdlName, methodName, timestamp, milliSeconds, otherProperties));
}
reader.close();
} catch (IOException e) {
throw new LogImporterException("Error reading log file: " + e.getMessage());
} catch (ParseException e) {
throw new LogImporterException("Error parsing logfile: " + e.getMessage(), e);
}
return logEntries;
}
用于填充地图的实用函数
private Map<String, String> parseOtherProperties(List<String> values) throws ParseException {
HashMap<String, String> map = new HashMap<String, String>();
String[] tmp;
for (String s : values) {
if (s.trim().isEmpty()) {
continue;
}
tmp = s.split(":");
if (tmp.length != 2) {
throw new ParseException("Could not split string into key:value :\"" + s + "\"", s.length());
}
map.put(tmp[0], tmp[1]);
}
return map;
}