java.net.SocketException: Too many open files

情況:
linux環境在沒動過任何code情況下，只有資料量變多，在執行下面程式時會噴
java.net.SocketException: Too many open files


原code：

StringBuffer sb = new StringBuffer();

String templatePath = PropertiesUtil.getProperty("MAIL_NOTICE_TEMPLATE_DONATE_PATH_IN_CLASSPATH");

InputStreamReader isr = new InputStreamReader(NoticeUtil.class.getResourceAsStream(templatePath));

BufferedReader br = new BufferedReader(isr);

String tmp = null;
try {
while((tmp = br.readLine()) != null) {
sb.append(tmp);
}
} catch (IOException e) {
log.error("讀取Notice html發生錯誤 for Award Invoic");
e.printStackTrace();          
return "";
}


Map<String, String> map = new HashMap<String, String>();
for (Iterator<AwardInvoice> it = aiList.iterator(); it.hasNext();) {
AwardInvoice ai = it.next();
map.put(ai.getPrizeType(), getPrizeInChinese(ai.getPrizeType()));
}




後來查一下之後發現可用 ulimit -a這指令查看目前系統資訊
 ulimit -a

core file size          (blocks, -c) 0

data seg size           (kbytes, -d) unlimited

scheduling priority             (-e) 0

file size               (blocks, -f) unlimited

pending signals                 (-i) 131072

max locked memory       (kbytes, -l) 32

max memory size         (kbytes, -m) unlimited

open files                      (-n) 4096

pipe size            (512 bytes, -p) 8

POSIX message queues     (bytes, -q) 819200

real-time priority              (-r) 0

stack size              (kbytes, -s) 10240

cpu time               (seconds, -t) unlimited

max user processes              (-u) 131072

virtual memory          (kbytes, -v) unlimited

file locks                      (-x) unlimited

可重新設定開啟檔案數

ulimit -n 8192

core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
file size               (blocks, -f) unlimited
pending signals                 (-i) 1024
max locked memory       (kbytes, -l) 32
max memory size         (kbytes, -m) unlimited
open files                      (-n) 8192
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
stack size              (kbytes, -s) 10240
cpu time               (seconds, -t) unlimited
max user processes              (-u) 16382
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

但想一想這或許不是解決辦法，後來又仔細看了一下code，發現下面兩行，使用完後沒有close掉，所以就試看看改成

InputStreamReader isr = new InputStreamReader(NoticeUtil.class.getResourceAsStream(templatePath));

BufferedReader br = new BufferedReader(isr);



修改後的code加了close：


StringBuffer sb = new StringBuffer();
String templatePath = PropertiesUtil.getProperty("MAIL_NOTICE_TEMPLATE_DONATE_PATH_IN_CLASSPATH");
InputStreamReader isr = new InputStreamReader(NoticeUtil.class.getResourceAsStream(templatePath));
BufferedReader br = new BufferedReader(isr);
String tmp = null;
try {
while((tmp = br.readLine()) != null) {
sb.append(tmp);
}
} catch (IOException e) {
log.error("讀取Notice html發生錯誤 for Award Invoic");
e.printStackTrace();          
return "";
} finally {
try {
br.close();
isr.close();
} catch (IOException e) {
e.printStackTrace();
}
}


再重新執行一次就沒噴了，以前學習時雖然都說要close覺得好像沒關程式也都可以run，就想
說有沒有關可能都沒差，結果在資料量大的時候沒關，果然還是有差！

所以以後還是要記得close