Hi all,
JBS: https://bugs.openjdk.java.net/browse/JDK-8242480
Webrev: http://cr.openjdk.java.net/~jiefu/8242480/webrev.00/
Negative values were returned by getFreeSwapSpaceSize() in our docker testing.
The reason is that current implementation doesn't consider the situation when
memory.limit_in_bytes == memory.memsw.limit_in_bytes, which means do not use
the swap space at all.
In
src/jdk.management/unix/classes/com/sun/management/internal/OperatingSystemImpl.java,
let's see
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71 public long getFreeSwapSpaceSize() {
72 if (containerMetrics != null) {
73 long memSwapLimit = containerMetrics.getMemoryAndSwapLimit();
74 long memLimit = containerMetrics.getMemoryLimit();
75 if (memSwapLimit >= 0 && memLimit >= 0) {
76 for (int attempt = 0; attempt < MAX_ATTEMPTS_NUMBER;
attempt++) {
77 long memSwapUsage =
containerMetrics.getMemoryAndSwapUsage();
78 long memUsage = containerMetrics.getMemoryUsage();
79 if (memSwapUsage > 0 && memUsage > 0) {
80 // We read "memory usage" and "memory and swap
usage" not atomically,
81 // and it's possible to get the negative value when
subtracting these two.
82 // If this happens just retry the loop for a few
iterations.
83 if ((memSwapUsage - memUsage) >= 0) {
84 return memSwapLimit - memLimit - (memSwapUsage
- memUsage);
85 }
86 }
87 }
88 }
89 }
90 return getFreeSwapSpaceSize0();
91 }
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If memSwapLimit (@line 73) equals memLimit (@line 74), then
getFreeSwapSpaceSize() may return a negative value @line 84.
It would be better to fix it.
Could you please review it and give me some advice?
Thanks a lot.
Best regards,
Jie
